What if you knew that you were going to be with a woman just for one night and then never see her again? Can you see how the fact that you couldn't possibly form a pair-bond might make the sex hotter, less inhibited?
I can see that happening easy.
The FWB thing is more inclined to start the caring feelings in many people. But I haven't hung around people like you or your sister and only have my one partner model to base anything on IRL. The academic models you talk about are easy to imagine happening. I act conventional/prudish/one woman-one man, but I can imagine it happening as you describe, just have to strip away lots of religious type moral values.
It's strange in a way, me talking about religious values when I ask some people at church, when I say to them "you do all this praying, then die and discover there is no God, then what?
Guess I am like Chrom, why ignore scientific evidence in some cases and not require it in other cases..
Can you see how the fact that you couldn't possibly form a pair-bond might make the sex hotter, less inhibited? What do I do If I knock her up? You know me, Mr responsability?