A lot of people get caught by that one. Reach the transition then come here to complain before going any farther.
I had already written the edit by the time you answered.
We're sorry that you don't understand the concept of the "N" in AVN and that such devices are common to prevent tedium and repetition. If every AVN takes precisely the same route, why play them?
Worrying about preventing tedium and repetition in the literal >first< sex scene in the game? Doesn't make sense.
Edit: Ok, it wasn't the first. It happened with his girlfriend a couple of times before, and MC had some flashbacks/sexual dreams. But still, very rare. The last thing dev should've done was to worry about preventing tedium and repetition and just delivering what took hours of playing (and for those who were following the releases since the beginning, it probably took months or years). After dev skipped the sex scene I almost rage quit this game, and I bet I'm not the only one. It was a poor choice of him.