Well, if you only do it with someone in a relationship, it can be your way of showing that you truly are close. Likewise, sometimes you just want the pleasure. In my case, when my boyfriend and I first started having sex, we would do it often. For us, often would be any chance we could get (3-4 times a week). But we questioned whether our relationship was in the right place, so we both stopped, and it didn't bother either of us. Nowadays, we're lucky if we can have sex at least 5 times a month... Lol, up until recently, neither of us had done anything for almost a month.