I’m sorry OP, seems like things probably hurt on a lot of different levels. Cheating is cheating & I am sorry it has happened twice now. I find your ex-partners are awful for not breaking up with you first if they really wanted to do something different + your sister also doesn’t sound too great of a personality lol. Really not cool! As for your part about the ex moaning louder with your sister, I wanted to say a few things. We live in a world where sexual education is very basic & people are not taught what really brings pleasure versus not. Yes there is pornography but it is not always depicting everyone’s preferences, maybe fantasies (and often it can skew reality).Your sister may have had time to figure her body out. So good news is you can ask your next partner what they really enjoy, or what they prefer. It may sound weird but it is the most logical thing to do, not only for yourself but to know the other person’s limits and preferences. Sexual communication is key and unlike what most people assume, no it is not just “common sense”. It requires communication!! Plus, what may be pleasurable to one person may not be to another so it’s really something that is always important to talk out. I know it’s almost assumed that we should “know” what makes someone moan their loudest but we aren’t mind-readers, nor are we educated enough about sex to always know. It comes with experience & talking.

so how do you feel now knowing you may have second hand eatin your sisters box?