Most of the educational psychologists believe that co-education can help the young people to have their sexual instincts activated so that they could release their sexual emotions easily during puberty. In contrast, Islamic educational authorities in Iran strongly insist that children arriving elementary schools must be separated and the teachers and textbooks are chosen according to their sexes. Therefore, men are teaching in boys’ schools and women in girls’ schools. There has been great effort to include men's pictures in boys’ textbooks to prevent from the sexual arousal. As there are not enough universities in the country, the university candidates are mixed in their classes and courses. This can bring flame to the ashes of hidden sexuality and involve the students in abnormal behaviours to control or suppress them. The conflict of interaction with the opposite sex in university with that in the family setting or even society has been proved to create depression among the first year students especially those coming from small and closed environments and rural settings. The statistics of referrals to the counselling office in the university show that self-involvement to control sexual instincts have been the great concern of the students. They spend most of their time thinking about their classmates of different sexes. This paper aims to study the psychological and social outcomes of suppressed instincts for young people having entered the university and the effect on marriage.