For me there is a vast difference between NSA and fb sex. This all occured many years ago.
Let me explain:
NSA always meant a one or two night stand ,or see you when I get back from Uni or in 3 months or maybe never. If they can't handle that and you want sex, it can't be with them.
Fb sex has one major string attached, that is we both want sex but nothing else ( much ) but we do both want to see each other again for sex ..
Yes it is difficult. I would never have tried anything kinky on an NSA, that is all about trust and it is rare you can fully trust someone after meeting them once or twice. Bondage and other trust based acts such as role play need full trust. Not only that you will take part but more importantly both sides are willing to say No and listen to No if the other side isn't interested
Fb sex ,well if you are getting attached to your partner you have a choice, end it or make your feeling known and risk them ending it or taking it to the next level.
It has nothing to do with being the local bike, I've always loved sex , if I was on my own apart from having sex with myself ( which I enjoy very much btw ) what else was I to do !.