The sex games I've enjoyed the most are the one's where I've been made to work for it. so I like the direction where you're going with this one.
it would better if you made progression less attainable but the rewards larger. this would increase the anticipation even more so since the reward means more and the build up is more drawn out giving the player more time to think about it. and you could tease the player too which would also increase the anticipation.
it's scientifically proven that unexpected rewards are more exciting than expected rewards as they stimulate more dopamine and adrenaline (who doesn't like a surprise blow job?). you could be the first to force random sex acts into your games at the most unexpected moments (no dialogue needed). adding a gambling element is also an excellent way to get this response while also adding an element of risk which is also exciting.