Through this research, we studied how love affairs affect the self identity and mental health of young people. We classified 109 male and 193 female undergraduate students into people in love and people not in love based on questionnaires completed by the students. As a results of comparing both groups, those who were in love reported high self-esteem, fullness scores and low depression scores in comparison with those who not in love. Those who were in love continuously tended to mark high brightness, friendliness, honesty, sensitivity, and the opposite sex role scores in comparison with those who were not in love. We discussed about the characteristics of young people in progress of personal relationships.