Young men typically experience their peak sexual activity, with the greatest number of different partners, in their 20s. Thus it is during this period that the risk for contracting STIs is highest, and the need to practise safe sex paramount.
Although sexual identity is usually well established by early adulthood, some young men only start to express it in their 20s. This is particularly true of homosexual men, who may delay ‘coming out’ because of fear of societal prejudice.
As men move further into adulthood, more permanent relationships, in the form of living with a partner or marriage, become prevalent. Those in long-term monogamous relationships may in fact engage in sexual activity more frequently than those with several partners. It is not unusual for some new couples to have sexual intercourse almost every day, but in general, among couples living together, the frequency of sexual intercourse tends to decline with time. Commitments and responsibilities such as forging a career and child-rearing can also mean that a couple has less time and energy for sex.
There is a slow decline in sexual functioning as men move through their 20s and into their 30s, but this does not become an issue for most men until later. From a peak at about age 18, there is a gradual decrease in the capacity for erection and ejaculation. Testosterone production starts to slow down after the mid-20s, with the result that men may notice that sexual responsiveness is slower.