Raman Thediya Seethai is the sweet-and-sour experience of a nearly-perfect man who embarks on a pursuit to find a life-partner. Though his endeavour does not give him a totally pleasurable experience, he gets into interesting associations on his way. What are his experiences and interactions with the strangers (including prospective brides) he meets? Does he finally find a suitable bride?

Venugopal (Cheran) designs and sells wedding invitation cards from his shop. When we say he is 'nearly-perfect ', what is his imperfection? Let's digress and go into flashback mode. As a young boy, Venu always wanted to fulfill his mother's wishes. When she had wanted him to be the top scorer in his school final exams, he pushed himself exceptionally hard, almost to the brink of a nervous breakdown. Consequently, young Venu had to undergo treatment at the mental health centre for a while. Though Venu became totally OK after treatment at the mental hospital, people around him still treated him as mentally unsteady. So is that the imperfection? No! The imperfection is - he is too honest and reveals his 'mental' episode and subsequent recovery to one and all!

When this gem of a man gets engaged to Ranjitha (Vimala Raman), in an attempt to be very truthful, he narrates this disturbing episode to her. However, immature Ranjitha does not accept it in the right spirit. She rejects him and cancels the marriage. A disappointed Venu eventually meets Vidhya (Ramya Nambeesan). Here, things progress to the point of fruition; but a day prior to the wedding, Vidhya elopes with her lover. When poor Venu is left in the lurch, Vidhya's father Manickavel (Manivannan) is touched by the young man's unassuming nature; he volunteers to stand by his side till Venu succeeds in finding a bride.

Next, Venu meets Nedumaran (Pasupathi), a visually challenged Radio Jockey, whose love for life lifts Venu's sagging spirits. Nedumaran's love story and his fairy-tale wedding with Tamizhisai (Kajala) amaze Venu completely. With renewed hopes, Venu travels to Nagercoil to meet Gayathri (Karthika). Venu's revelation of his past does not deter the cheerful Gayathri from the proposal; however, Venu is forced to change his mind when he learns about Gayathri's unfulfilled love affair with auto driver Kulla Sekar (Nitin Sathya). Accidentally, Venu also meets Vidhya during his stay in Nagercoil when she is on her way to the hospital to deliver her first child. Venu learns about her miserable life; when he offers to pay her bills, he meets Ranjitha at the hospital's reception counter. With a genuine concern about Vidhya's well-being, Venu meets Inspector Senthamarai (Navya Nair) the final candidate on his list. An unexpected happening messes up their meeting and alters their first impressions about each other. An injured and frustrated Venu comes to Ranjitha's house to rest and recover from the disturbing episode. Mulling over his expereinces, he makes an important decision about his life at that juncture. What is that? Does he decide to support the struggling Vidhya? Does he marry Senthamarai or does Ranjitha appeal to him as the best choice? Does Venu finally find his mate? Raman Thediya Seethai spins an intriguing tale!