Lord Rama never ever disowned Sita, nor did He ever want Sita to perform the fire test - Agnipariksha. 

Rama is an avatar of Vishnu. Avatars come to earth on different missions and a different plan of action. The manifold activities of the Supreme Lord during an avatar are called "Leela". It signifies the Lord being completely absorbed in His role as a mortal, adhering to every earthly law, whether man-made or natural; but keeping His divinity intact. Lord Rama in the Treta Yuga is given the title of Maryada Purushottam because He displayed traits which should ideally be present in every human to the closest possible degree. Dharma would naturally and freely flourish in this manner. He was the epitome of morality, humility, versatility, sense-control, character, courageousness, fortitude, fearlessness, wisdom, gratitude and prudence. He was learned in the rules of grammar, the poetic meters and astrology. He also mastered the 4 Vedas. In addition, He was skilled in the art of warfare, ethics and was the greatest archer to ever set foot on earth. Such a person is worthy of being emulated. That is why He was born in the Treta Yuga, because since this Yuga had 3 legs of Dharma, there was room for absolute righteousness, with small 'loopholes'; for example the killing of Bali and the Agnipariksha of Sita; which people nowadays view with a belittling stance towards Rama. In this way, they fail to realize that those 'loopholes' were in no way any sort of Adharma, and many start disliking the blemishless Rama, who was the very personification of Dharma. (In a later section I will discuss why Lord Rama did such 'apparently' unfair acts). The plain reason for the dislike is that it is impossible for mundane people in Kali Yuga to understand the wide subtleties of Dharma, especially that which is subtly displayed by the Lord (Who has the perfect knowledge of Dharma). Even wise Jnanis fail to understand the subtleties which can ONLY be understood by a sincere and true Bhakta.

<br>

> Narada describes Rama in the Valmiki Ramayana as follows - 
> 
> इक्ष्वाकु वंश प्रभवो रामो नाम जनैः श्रुतः |<br> नियत आत्मा महावीर्यो
> द्युतिमान् धृतिमान् वशी || १-१-८
> 
> "One emerged from Ikshvaku dynasty and known to people as Rama by his
> name, and he is conscientious, highly valorous, resplendent, steadfast
> and a controller of vice and vile... and his own senses, as well...
> [1-1-8]
> 
> बुद्धिमान् नीतिमान् वाङ्ग्मी श्रीमान् शत्रु निबर्हणः |<br> विपुलांसो
> महाबाहुः कंबु ग्रीवो महाहनुः || १-१-९
> 
> "He is an adept one, moralist, learned, propitious, and a destroyer of
> enemies. His arms are lengthy, and his neck is like a conch-shell, and
> cheekbones high... 
> 
> महोरस्को महेष्वासो गूढ जत्रुः अरिन्दमः |<br> आजानु बाहुः सुशिराः
> सुललाटः सुविक्रमः || १-१-१०
> 
> "He is lion-chested, thick-shouldered, knee-length are his arms, and
> his is longbow, an enemy-subjugator, and his emperor's countenance is
> with a crowning-head with an ample forehead, and his pacing is
> lion-like...
> 
> समः सम विभक्त अंगः स्निग्ध वर्णः प्रतापवान् |<br> पीन वक्षा विशालाक्षो
> लक्ष्मीवान् शुभ लक्षणः || १-१-११
> 
> "He is medium-sized physically, with limbs poised symmetrically,
> sinew-chested, wide-eyed, complexioned glossily... he is a prosperous
> personality with all the providential features, and thus he is
> self-resplendent...
> 
> धर्मज्ञः सत्य सन्धः च प्रजानाम् च हिते रतः |<br> यशस्वी ज्ञान संपन्नः
> शुचिः वश्यः समाधिमान् || १-१-१२
> 
> "He is the knower of rectitude, bidden by the truth, also his concern
> is in the welfare of subjects, proficient in prudence, clean in his
> conduct, self-controlled and a diligent one, thus he is glorious...
> 
> प्रजापति समः श्रीमान् धता रिपु निषूदनः |<br> रक्षिता जीवलोकस्य धर्मस्य
> परि रक्षिता|| १-१-१३
> 
> "He equals the Omniscient, he is an exalted one for he is the
> sustainer of all worlds, and he eliminates enemies completely, thus he
> is a guardian of all living beings and he guards probity, in its
> entirety... 
> 
> रक्षिता स्वस्य धर्मस्य स्व जनस्य च रक्षिता |<br> वेद वेदाङ्ग
> तत्त्वज्ञो धनुर् वेदे च निष्ठितः || १-१-१४
> 
> "He is the champion of his own self-righteousness and also champions
> for adherent's welfare in the same righteousness, and he is a scholar
> in the essence of Veda-s and their ancillaries, too. He is an expert
> in dhanur Veda, the Art of Archery...
> 
> सर्व शास्त्र अर्थ तत्त्वज्ञो स्मृतिमान् प्रतिभानवान् |<br> सर्वलोक
> प्रियः साधुः अदीनाअत्मा विचक्षणः || १-१-१५
> 
> "He is the knower of the meaning and essence of all the scriptures,
> excellent at memory thus brilliant, and an esteemed one in all the
> worlds, gentle, level-headed and clear-headed in discriminating and
> distinguishing...
> 
> सर्वदा अभिगतः सद्भिः समुद्र इव सिन्धुभिः |<br> अर्यः सर्वसमः च एव सदैव
> प्रिय दर्शनः || १-१-१६
> 
> "Like an ocean that is reached by many rivers accesbly, that
> reverential one too is always accessible and reachable by clean-minded
> ones, and he treats all equally, and ever a feast to eye...
> 
> विष्णुना सदृशो वीर्ये सोमवत् प्रिय दर्शनः | <br> काल अग्नि सदृशः
> क्रोधे क्षमया पृथ्वी समः || १-१-१८ <br> धनदेन समः त्यागे सत्ये धर्म इव
> अपरः |
> 
> "In valour Rama is comparable with Vishnu, and in his looks he is
> attractive like full-moon, he equals the earth in his perseverance,
> but he is matchable with the fire of Pralaya in his wrath... and in
> benevolence he is identical to Kubera, God of Wealth-Management, and
> in his candour he is like Dharma itself, the other God Probity on
> earth...
> 
> तम् एवम् गुण संपन्नम् रामम् सत्य पराक्रमम् || १-१-१९ <br> ज्येष्टम्
> श्रेष्ट गुणैः युक्तम् प्रियम् दशरथः सुतम् | <br> प्रकृतीनाम् हितैः
> युक्तम् प्रकृति प्रिय कांयया || १-१-२० <br> यौव राज्येन संयोक्तुम्
> ऐच्छत् प्रीत्या महीपतिः |
> 
> "Rama being the possessor of suchlike merits, whose truthfulness alone
> is his courage, embodied with best intrinsic values, ever involved in
> the welfare of people, besides being the dear and eldest son of
> Dasharatha, and hence the king Dasharatha affectionately intended to
> establish such a Rama as crown prince to all intents and purposes of
> country's welfare...
> 
> ......... <br> .........
> 
> स जगाम वनम् वीरः प्रतिज्ञाम् अनुपालयन् |<br> पितुर् वचन निर्देशात्
> कैकेय्याः प्रिय कारणात् || १-१-२४
> 
> "Such a brave one as he is, that Rama repaired to forest for the
> reason of appeasing Kaikeyi, and as directed by the verbal directive
> of his father, and to follow his father's word of honour.

Such a Man, Whose description exceeds far beyond the capacity of mere mortal words, Whose effulgence is brighter than the multiverse combined, Whose virtues are greater than the universe itself, how can He who is divinity manifested in flesh, ever suffer? Sita, Rama's consort, is said to be an avatar of Lakshmi, who was Vedavati before the present birth. Needless to say, they are divine spirits, they never suffer, they just appear on earth time to time and depart when their work is done. As I've said before, avatars are continually engaged in Leela, invoking various types of "rasas" or "moods" of blissful love between man and God. 

The Agnipariksha was never an intention of Rama, albeit that had to be done because the Sita who was kidnapped by Ravana was no other than an illusory form of Sita called Maya Sita. This story, retold in Caitanya caritamrta 2.9.200 - 212, appears in Kurma Purana 2.34.111 - 140.

> 111. A chaste woman devoted to piety (dharma) shall always attain welfare and happiness. No man can, by any means, create discomfiture
> for her.
> 112. Just as in the case of Sita,1 well-known in the three worlds, as the charming and beloved wife of Rama, the son of Dasaratha, she
> conquered the king of Raksasas.
> 113. Urged by Kala (Death), Ravana, the king of Raksasas, desired Sita, the wide-eyed beautiful wife of Rama.
> 114. It is reported that by means of his Maya, he disguised himself (as) an ascetic and determined to abduct that beautiful lady while she
> was strolling (solitarily) in the tenantless forest.
> 115. The lady of pure smiles realised his intention. Remembering her husband, the son of Dasaratha, she sought refuge in the Avasathya
> (household) fire.
> 116. With her palms joined in devotion, Rama's wife worshipped the great Yogi (the fire-god), the destroyer (scorcher) of the worlds, as
> if he was her husband Rama incarnate (and prayed): Eulogy of the
> Fire-god.
> 117. I bow unto Krsanu (fire) of the form of Kala, of great Yogic power, the greatest riddle, the destroyer of all living beings.
> 118. I take shelter in lord Pavaka (the purifying deity), the eternal deity of universal forms, the Yogin who wears the (elephant) hide, the
> lord of the goblins, the Supreme god.
> 119. I resort unto the Atman of radiant blazing body abiding in the hearts of all living beings. I seek refuge in the Lord whose form is
> the universe, the source of all that fiery, brilliant. I resort to the
> fire-god, the Lord of great Yogins, the sun, the supreme god.120. I
> seek refuge in Rudra, the great swallower (destroyer), the
> trident-bearing Lord, the fire of the Universal destruction, the Lord
> of Yogins, the dispenser of fruits (in the form) of enjoyment and
> liberation.
> 121. I resort unto you the diverse-eyed deity with the forms of Bhuh, Bhuvah and Svah}, one who is lying hidden in the golden abode, the
> great one of unmeasured splendour.
> 122. I resort to Vaisvanara abiding in all living beings, the lord who conveys Havyas and Kavyas (i.e. offerings) (to gods and Pitrs). I
> resort to Lord Vahni.
> 123. I resort to that Supreme reality, the excellent and auspicious principle of the sun. I resort to the Agni ascending to heaven, the
> greatest splendour, the imperishable conveyor of oblations to gods.
> 124. After repeating (the prayer in) these eight (?) verses on Vahni, the famous wife of Rama mentally meditated on Rama and remained silent
> with her eyes closed.
> 125. Then out of the Avasathya (household) fire, Lord Mahesvara (the great god), the bearer of sacrificial oblations, of resplendent soul
> manifested himself as if burning with his own refulgence.
> 126. Desirous of getting Ravana killed he created an illusory Sita. Taking the real Sita, the beloved of Rama, the fire-god vanished
> there.
> 127. On seeing such a Sita (i.e. the illusory one) Ravana the lord of Raksasas, took her and went to Lanka, situated within the ocean.
> 128. After killing Ravana, Rama took Sita and (came back) accompanied by Laksmana. His mind became agitated due to suspicion.
> 129. For convincing the living beings, the illusory Sita entered the fire; immediately she was consumed by the fire.
> 130. After burning the illusory Sita, the lord fire-god of hot rays, showed the real Sita to Rama. The fire-god (the purifier) became a
> beloved of Devas.
> 131. Catching hold of the feet of her husband, the daughter of Janaka, the lady of beautiful middle, made obeisance to Rama on the ground.
> 132. On seeing it Rama was delighted in mind. Surprise was evident in his eyes. After bowing to the Vahni with bent head, Raghava
> propitiated him.
> 133. The lord spoke to Vahni: Was this fair-complexioned lady burned by you before, as she has been seen come to my side again?
> 134. Lord Fire-god, the scorcher of the worlds, spoke to the son of Dasaratha, telling him everything as it had happened in the presence
> of all living beings.
> 135. "This beloved of yours is highly chaste as goddess Parvati. She is the greatest favourite of the goddess whom she had propitiated by
> means of penance
> 136. This chaste lady of good conduct is endowed with the readiness to serve her husband like Bhavani in regard to Isvara. She was protected
> by me because she was desired by Ravana.
> 137. But Sita who was abducted by the lord of Raksasas was the illusory Sita created by me with a desire to get Ravana killed.
> 138. On that account, Ravana, the wicked king of the Raksasas and the destroyer of the worlds, had been killed. The Maya has also been
> withdrawn.
> 139. "Accept this pure Janaki at my instance. See lord Narayana your own self the source of origin and the place of everything".
> 140. After saying this, the fierce lord fire-god whose flames spread everywhere and who had faces on all sides was duly honoured by Raghava
> and the other people and he vanished.

Thus we see that Maya Sita was just an illusion who went back to Agnidev through the Agnipariksha while Agnidev himself brought out the real Sita to Rama. At that moment Rama (who definitely knew everything) was (just for a show to the common public) very happy and elated. The Agnipariksha was done for 2 major reasons. **1> Return of Maya Sita back to Agnidev, and 2> A foolproof convincing of the common public that Sita was not unchaste, as a disgruntled public would not be beneficial for Ram Rajya** This was a risk which Rama had taken on his own honour. While its true that people were speaking ill about Sita, they all stopped in their tracks when they witnessed the apparently "cruel" act of Rama. Everyone’s emotions are running high. They know what they have witnessed. By this time they knew Sita was pure, even purer than fire itself. Rama had achieved his motive.

If you think that the motive of Rama was to prove to himself that Sita was pure then you are absolutely wrong. His motive was to prove to everyone what he already knew, it was to make people realize that a woman who stayed in other man’s custody for around a year is still as pure as Ganges, it showed everyone that Sita’s devotion to her husband is something which even a powerful king like Ravana could not challenge. Rama on the risk of being brought down from his high podium, makes sure that no one ever raises a
suspicion on his wife. Risking his own respect in society to restore his wife’s honour.

Following this event, they went back to Ayodhya and lived happily. What followed was the famous Ram Rajya. Then a washerman named Krodhana raised some suspicion on Sita, and Rama sends her to Valmiki’s ashram. He didn’t leave her alone in any forest as contrary to common belief, he asked Lakshmana to take her to Valmiki’s ashram and Lakshmana does exactly the same, except however Lakshmana drops her on the gates of ashram rather than taking her inside, maybe because he was too terrified to face his guru while indulging in such an act (which according to him was unjustified).

The separation had to be done to display the exemplary detachment of a "dharmaraja" or a just king. People argue that Sita was family, so family comes first. But they forget that Rama and Sita were not just another family of Tom Dick Harries. Rama also had a duty which was called Ram Rajya, wherein NO subject could be subject to any sort of frustration or irritation, whether bodily or mental. In governing a kingdom, or Raj Dharma, one must not be swayed by personal emotions, as it would lead to a sort of cloudiness over the otherwise rational part of the intellect - Emotions vs Logic. When emotion takes over, logic fails, which may lead to crucial errors. Be it wife, son, daughter, anything; Raj Dharma takes into consideration millions of lives in the hands of the monarch. Rama couldn't just play with their lives for His family's comfort, which would be selfish on His part. Western colonized minds do not have "Bhakti" and "Shradhha", which is detrimental while judging Vedic characters.

From Rama and Sita's Leela point of view, this act of separation was done to invoke the mood of love while being separated, which is regarded as the strongest attraction between lovers. Mundane people abuse and curse Rama for such behaviour. In the process they only lower their consciousness to extreme darkness. Bhaktas on the other hand cry tears of joy and sing His Transcendental Glories and elevate themselves more and more towards the Brahmajyoti and into the Vaikuntha planets and even higher.

God who came to earth in the form of Rama, who is supposed to be the source of inspiration for every human being doesn’t even think twice before putting himself under the sword of criticism, just for the love of his wife, for her Honour. Rama's Honour got a second blow when He (purposely) renounced His wife and sent Her to Valmiki's Ashram; an act which made people think about Sita again. In the end by putting a blemish on his persona of ***MARYADA PURUSHOTTAM***, Rama raises Sita above all suspicions.
This can be accounted for - <br>
<br>
**The greatest love. <br>
The greatest sacrifice.** <br>