This somehow makes perfect sense, this guy was the weirdest character in this manga by a longshot - seemingly nice and understanding, and I don't even think he was faking it, but simultaneously having a scheming nature and being dead set on getting together with Rui, and this chapter was all about resolving that conflict. His conclusion that Rui might not be worth the trouble is probably correct
What I'm slightly curious about is if we're ever going to have an appearance of the parents in this, because it's pretty clear that they're supposed to be the real villains and settling things with them is the most straightforward solution to Rui's problems (whether reconciling or telling them to go fuck themselves it doesn't really matter), but instead we got Itsuki continuing to be this weird troublemaker, and the author achieved that by quite unconventional means

I like it though, it's pretty fun so far and I guess this is all that matters, right?