The myth that you can do anything you want as long as it doesn't hurt anyone has such momentum, that it seems as if it will never die. This "rule" has been applied especially to sexual activity (I mean, what else is there to live for, after all?), and it has been applied across the board. The only caveat among the remaining bit of sanity in our culture is that whatever sexual perversion someone wants to engage in, it should be with a consenting adult. Never mind where such a moral law comes from, or why someone should obey it, and neither in the least do people have any clue as how to define an "adult." Is it when a boy is able to sire a child (12-14)? Is it when a girl is able to carry a child in the womb (12-14- or earlier is she eats a lot of chicken raised with hormones)? Is it when they can drive (16), or vote (18), or kill the enemy in battle (18), or when they can order an alcoholic drink (21)? Or, is it when they graduate college, or even later - when they are off their parents' health insurance (26)? Well, never mind those terrible details of what it means to "be" a man or a woman; we should just accept the First Great Commandment that "two (or more) consenting adults should be able to do what they want in the bedroom as long as they don't hurt anyone." And the Second is Like Unto It: "You shall not judge them for doing so." These are the two great commandments of our culture today.
But it doesn't really work that way, does it? People don't like being used. There's a lot of emotional baggage, and yes, deep damage to a person's inner self after consenting to Person A, Person B, Person C, and so on, ad infinitum. Like tearing of a bit of paper from a sheet, each time two people consent to "casual" sex, one tiny tear comes off that paper, and then another, and then another, until all that is left is a tiny little ripped piece, alone and scattered, lying in the drifting tatters like the rest. Numbness sets in, and when someone's "true love" finally arrives, it's too strenuous to create that emotional bond that will last forever. Maybe this relationship will work; but then again, maybe it won't. Maybe relationships aren't meant to work, after all, you say. "Do whatever you want as long as you don't hurt anyone." How's that working so far?