Jimmy... Dead.
contemplative curmudgeon
Obviously people in their twenties have sex; so we can assume they know how. What you seem to be arguing is that older people have an emotional or ethical maturity that inhibits promiscuity (or something like that; more specifically, it would inhibit two people who care about each other from ruining a casual relationship with sex). I'm arguing that there is no reason to assume: a) that older people are more ethically mature than people in their twenties, and b) that this "maturity" has anything to do with two people continually falling back into a sexual relationship.
Intelligent, successful, polite people rationalize how they can get sex all the time; sex is a huge motivational factor. This has nothing to do with immaturity; it's just biology. "Maturity" takes on an ideological significance in this situation because it attributes an illusory qualification to refraining from said behavior. In truth, what we perceive as "immaturity" tells us nothing about the true nature of why two people engage in said behavior; you can't just boil it down to "well, they're immature."
Immaturity is a completely relative and unreliable gauge of any behavior because there is no objective standard against which it can be measured. Qualifications of age are ideologically instituted (why can someone go fight in a war at age 18 but can't legally drink until 21; where's the "maturity cut-off"?).
All I'm saying is personal maturity is the first prerequisite for a mature intimate relationship.
Of course biology has something to do with it, the body’s internal structures, sexual desires, has the greatest influence on intimate behavior. Typically, each person’s private, often secret or suppressed, sexual desires surface. Each seeks to please and gratify the others wishes. Negative feelings will tend to be withheld in order to avoid disapproval or rejection. Eventually other personality factors will surface. Levels of maturity with respect to intimacy, however, inevitably will begin to affect the harmony and quality of the relationship.
Ones level of maturity with respect to intimacy has a powerful influence over the success of interdependency. If both persons in the couple had a high level of maturity when considering and choosing a mate, then concern with maturity with respect to many aspects of the way the relationship is conducted becomes increasingly important to each person the longer they live together. The greater the degree of maturity of both parties, the greater is the possibility that the quality of the relationship will improve over time.