Men initiate sex more than three times as often as women do in a long-term heterosexual relationship says a study. The researchers investigated what are the other factors which play a role for the frequency of intercourse in couples in long-term relationships. The study published in the journal Evolutionary Behavioral Sciences suggests that two factors are decisive in how often women take the initiative at all -- their attitude towards casual sex and passion. The researchers considered several factors in their study such as how happy people are in their relationship how committed they feel to their partner how intimate