You may wonder why teen-age girls -- but not teen-age boys -- spend all that time making laundry lists for what they want in an ideal mate. A study by UC Davis psychologist Richard Robins reveals the answer: Women have higher expectations for what makes a happy relationship. In a study published in a recent Journal of Personality and Social Psychology, Robins looked at how both partners' personality traits shape the quality of their relationship among 360 young couples. "There were a number of ways in which the man's personality influenced his partner's level of happiness and likewise, a few ways in which the woman's personality influenced her partner's happiness," Robins says. He looked at three scales of personality: one for negative emotions such as fear, anxiety and anger; one for positive emotions and the tendency to view life as an essentially pleasurable experience; and one for constraint, or acting in a cautious and restrained manner, avoiding thrills and conforming to social norms. Robins found that while a man's relationship happiness is predicted only by his partner's low level of negative emotions, a woman's happiness depends on that low level of criticism and anxiety plus a high level of positive emotions and constraint. Men who rate high on the positive emotionality scale may be better at using humor and other behaviors to defuse conflict, Robins suggests. In addition, the reason women are more satisfied with men who are not impulsive could be because they are better long-term prospects as husbands and fathers.