According to Ramayana, Lord Hanuman was a Brahmachari (celibate/bachelor). Why did he decide to spend his life as a celibate? What is the reason behind it?
No, Hanuman was technically not a bachelor (Brahmachari). His wife was Suvarchala who was the daughter of Surya (the Sun god). According to Surya, Suvarchala was an ayonija (born without [the participation] of the yoni).
Because he wanted to learn Nava Vyakarnas (the 9 Grammar Rules), he has to marry, and being an Aajanma Brahmachari (life-long bachelor), Hanuman was not eligible to study it. Surya grants him a boon that he will still be a bachelor even after marriage as a Prajapatya Brahmachari and will maintain his celibacy.
I agree with mjosh, Lord Hanuman is married to Suvarchala Devi. Because He Himself is a god(rudra amsa), who has self realization, decided to live a noble life with no space to world marital pleasures. For Him Rama seva(service) is everything and dedicated His entire life in Rama seva. He is not bramhachari but practices bramhacharya.
Sanathana dharma recommends bramhacharya as it keeps all sensory organs, mind, heart under one's own control. It boosts memory and gives mental & physical stability and strength.
Brahmacharyam means celibacy. I would like to clarify that marrying a woman will not disqualify anyone to become brahmachari (celibate). The man who do not discharge (veerya skalanam) his semen is called brahmachari. Even after the marriage a man can be bhrahmachari without having intercourse with wife. This is a very deep subject and one needs lot of wisdom to understand this concept. A man can be brahmachari even after having intercourse with a woman. There are many perfect brahmacharis in Hindu scriptures, Bhishma and Hanuma are best among them.
It is right that Lord HANUMAN was married to SUVARCHALA. As sun means rule "niyam" and out of 8 kala only 3 could be given to unmarried so for the rest 5 sun himself suggested this option to HANUMAN. The marriage was just for the name sake and did not resulted in further activities of marriage or dissolution of brahsmashcharya for Lord HANUMAN. Lord sun himself was witness to the marriage and also for the purity and non-involvement of Lord HANUMAN in the normal aspect of marriage. So the marriage was just name sake to maintain the rule of giving the knowledge of 5kala to Lord HANUMAN.
I do not know of any stories regarding the marriage of Hanuman to a daughter of Sun God. There are various stories created by different writers in India regarding the lives of Mythological Characters which have a local circulation.
One need not comment on them. The story of Hanuman marrying Sun God's daughter, is not accepted all over India.
The story of Hanuman remaining unmarried is, however, common knowledge. It is believed that Hanuman lives as a Spirit for Ever to help distressed Souls .Bodies that live for Eternity like the Earth and Nine Planets and Stars in Heaven, are all lonely bodies.
So it is believed in Hindu Philosophy, that all those who live for Eternity, should be Lonely Characters. The existence of Twin Stars, which co-exist by revolving around a common centre, was not known to the Philosophers of the Past.
As Hanuman is known to all of us from the Legendary Itihasa "Srimath Ramayana" the holy scripture which was visualised and presented by the great Sage Valmiki. Valmiki Ramayana is the only Ramayana that is authentic for all the references and discussions about any body related to this itihaasa. Rest all Ramayanas which are written by great bhaktas and Scholars are baising on their own vision and experiences that they have with the almighty. but can be considered as their own experiences but not as authentic. One of such work is "Parasara Samhitha" which is written in the very recent times and not ancient. It was said that it is not even written by the great sage Parasara as it has very minute grammar mistakes in it. The so called parasara samhitha has given such explanations about Lord Hanumans marriage and Hanuman having Camel as Vahana which are base less.
As far as Suvarchala is concerned, she is not the daughter of Surya but his wife. It was clearly said in Valmiki Ramayana by Goddess Sita to Rama. At the time Rama is leaving to Vanavasa.. He requests Goddess Sita to stay back at Ayodhya. Then Goddess Sita explains to Lord Rama that " like Sachi devi will not be away from Lord Indra, As like Suvarchala Devi will not be Away from Lod Surya. AS like Arundhati will not be away from Sage Vashishta .. I will not and can not live away from You " "Yatha Suryam Suvarchala " is the part of the Stranza from Valmiki Ramayana - Ayodhya Kanda.
So Hanuman is Brahmachari. Suvarchala is the wife of Surya and not the daughter according to Valmiki Ramayana.
Brahma= universal consciousness Charya= means INTRER MINGLE=UNITED
So the meaning of brahmachary is not celibacy, the person who known the Brahma/ universal wisdom.