In the Ramayana the marriage of Lord Rama is done in the most auspicious of manner. There was selection of dates by the greatest of sages and also astrology. Yet there is suffering and struggle of marriage between Lord Rama and Sita.
As per Uttara Khanda, Sage Durvasa had already foretold the sufferings of Rama and Sita to king Dasharatha -
Learn, O King, what happened formerly during the conflict between the Devas and Asuras. The Daityas, whom the Suras threatened, took refuge with the consort of Bhrigu and she, having given them a haven, they dwelt there in safety. Seeing them thus succoured, the Chief of the Gods, enraged, with his sharp-edged discus severed the head of Bhrigu’s wife. “‘Beholding the murder of his consort, Bhrigu, in his wrath, instantly cursed Vishnu, the destroyer of enemy hosts, saying:— “Since in thine insensate fury, you have slain my spouse, who should never have died thus, you shalt take birth in the world of men, O Janardana, and there you shalt live separated from your consort for many years.” “‘Having pronounced this curse, Bhrigu was overcome with remorse and his merits being exhausted by the malediction he had uttered, he began to propitiate that God, paying homage to the One who delights in penance and protects his devotees. Thereafter that God spoke, saying, “For the good of the worlds, I will be subject to your curse.” “‘This is how the illustrious Vishnu was cursed by Bhrigu in days of yore and descended on earth, becoming your son, O Foremost of Monarchs. Renowned in the Three Worlds under the name of Rama, he has to undergo the dire consequences of Bhrigu’s curse. He will reign in Ayodhya for a long time. Those who follow him will be happy and prosperous and, having reigned for eleven thousand years, Rama will go to Brahmaloka. Having performed many great sacrifices, distributing costly gifts, he, who may not be overcome by the most powerful beings, shall establish many dynasties and he will beget two sons by Sita.’
Sarga 51, Uttara Kanda
No one was fooling anyone it's just blessings and curses both takes their turns one by one. There were many curses to Lord Vishnu like curse by Mata Saraswati, Narada, Vrinda, Bhrigu, curse to Narasimha, etc mentioned in different-different scriptures.
Even Lord Rama knew it to some extent.
Sri Valmiki Ramayana.:
"I might have definitely, habitually, and desirably committed damnable deeds in my previous births, and now the result of those impious deeds is very much ripened and has fallen on me, whereby I am entering misery after misery"... [3-63-4].
"I am deprived of the kingdom, departed from my own people, mainly Seetha, my father departed and I am detached from my mother, and Lakshmana, when all these setbacks are very deeply thought over they are replenishing the haste of my agony"... [3-63-5].
I hope this helps. Prd..
