here are some statistics i've found on human behaviors.
“Second, the age of first marriage has been rising--in 1960, first marriages occurred at age 20.8 for women and 22.8 for men; in 1998, it was 25 for women and 26.7 for men (U.S. Bureau of the Census, 1999). The effect is a substantial lengthening of the time between biological readiness and marriage; the gap is typically 12 to 14 years today”
“Satisfaction with one's sexual relationship is an important component of sexual health. While many factors may contribute to satisfaction, three that differentiate people who are happy from those who are not are (a) accepting one's own sexuality, (b) listening to one's partner and being aware of the partner's likes and dislikes, and (c) talking openly and honestly (Maurer, 1994). In other words, successfully completing the developmental tasks of adolescence and young adulthood are keys to sexual health.”
Human sexual development - Statistical Data Included. Journal of Sex Research, Feb, 2002, by John DeLamater, William N. Friedrich
“The study of romantic relationships has linked positive affect to sexual desire and behavior (Berscheid, 1988; Regan, 2000). It is not surprising that when partners indicate love and positivity toward each other, and define the relationship in positive terms (e.g., satisfied, intimate, and committed), they are more open to sexual experiences and more likely to report sexual involvement. As Giles (2004) states, "Love is but one more way of wanting what sexual desire wants: mutual vulnerability and care" (p. 171). Cooper, Shapiro, and Powers (1998) showed that after people engaged in sexual interaction with their partners, they expressed more positive feelings and felt more connected to them. It would seem that positive feelings toward one's partner anchor the sexual experience, pull partners toward each other, and create a relational context for pleasurable sexual interaction.”
Sexual expression: its emotional context in heterosexual, gay, and lesbian couples. Journal of Sex Research, July-Sept, 2008, by Carl Ridley, Brian Ogolsky, Pamela Payne, Casey Totenhagen, Rodney Cate