We think that sex is natural, instinctual, and this is how it starts. We have our first experiences, some of them might not the best ones. Puberty, teenager hood so confusing and with hormones all over the place, eventually we make it through. Sometimes we are left with questions or we have preferences and tastes that are "different", difficult to share with others. Our best teachers are peers and friends and sometimes porn and online images. The expectations are set, but maybe we don't feel they match our desires or our partner/s expectations, probably not our parents one either.
Sex when you get older? Such a taboo, imagining your grandparent having sex? Uh!
Sex has not got age or gender or rules apart the main one consent.
I hear stories of random sex, not particularly good where people do not talk on what they like or expect, and they feel used and abused. Or people giving up sex when the physical issues arise, easier than to talk about it. Lots of confusion around sex and intimacy, mixed and confused with feelings.
What about affairs? Open relationship? Poliamory? There is so much our there that could be scary to look at, but we can be curious or bored and maybe fantasise about it. Even try something randomly