Actually when I was first going to reply I thought someone had said as long as "no one gets hurt" but then. I couldn't find that some one had said that..
That was mentioned quite a few times in the previous pages. E.g.
No, it seems to be a drift towards wanting everyone to conform to ones view of how things should be. Which is in the same league as the religions nutters wanting gays killed and women covered up from head to toe, albeit less extreme.
I still fail to see how consenting acts affect your notion of 'social order'. When violence or harm is inflicted on unconsenting beings - human or animal, that should be a cause for concern.
+1000000
As long as you are an adult practicing safe sex, using condoms, not taking advantage of people who are drunk or otherwise intoxicated, protecting yourself from STDs and unwanted pregnancies, and you are not physically harming or emotionally scarring yourself or someone else, there is no reason not to go and enjoy casual sex with other informed consenting adults who also want to have sex for the sake of sex.
Of course emotions get entangled, and that is something to watch out for, both in yourself and in your sexual partners.
Go and shag and have fun (safely) or stick to one (or two or three) people. Just don't try and impose your way on everyone else.
As for cheating/adultery, that is more of a result of forced monogamy and a culture that treats people like property. Nobody can legislate adultery away.