JUST. LET. HER. FUCK. YOU.
YOU ABSOLUTE BETA JAPANESE MALE.
If the protagonist was someone who was farsighted, then you could come up with a reason on why you don't want to fuck her. Maybe because then she will leave, so you are teasing her until she falls in love and stays. But this MC, is absolutely NOT someone who has the capacity for critical thinking, so that reasoning doesn't apply here.