I think it's a bit more nuance then that. No one can choose who they fall in love with. The ML has his own issues mostly including those around his past relationship to sort out. If he doesn't give himself and others around him 100% clarity on those issues, the FL will constantly feel like she's the rebound for a rocky relationship. The new relationship will quickly grow toxic if both sides don't have solid mental and emotional stability with themselves and each other.
I'm the same way. I really like the way it seems to try exploring the nuances of romantic and sexual attraction. I didn't expect actual plot outside of nonsense smut, a bit of fluffy romance, and the hilarity that ensues from it within something titled "Thank You For Erecting To Me". However this is a smut piece, so I may just be reading too much into it. I tend to do that a lot as if I'm forcing myself to like it more than I should to satisfy my boredom.

WHY! If Subaru is willing to accept her and likes her why can't she go with him while the other guy is being selfish and can't accept her feeling yet. Why are you being so dumb woman(╯°Д °)╯╧╧