The problem lies with Maiko being the only one who values him. He's already too attached to her and feels compelled to do this.
He feels the world is beautiful because she spends time with him and that until meeting her his life was not worth it.
Before this whole impregnating thing even happened their relationship dynamic was already fucked up.
As much as mc seems to dislike this between going back to the days without Maiko and doing want she wants it's pretty easy to know which he'd pick. And unfortunately Maiko knows this.
Hey hey, more importantly: If he did bail, the story would be either normal or over.
If those are the stakes, and his moral calculus, then I kinda don't care how wonewy he's afraid of being, just like I don't care how equally afraid of losing Maiko the girlfriend is, or how low Maiko's self-esteem is due to trauma - I'm just not going to be able to emotionally/sympathetically connect when we start talking about excuses to bring a baby into an abusive situation.
Probably not a reaction the author was counting on, and that's fine.
I dunno if we'll be asked sooner rather than later to start caring about all of them, or if the designed appeal is one like a slasher movie for feelings, "Watch and laugh as they hurt each other," but I'm already at "Nah."
I get that this is probably catnip for some demo of people that like being denied/cucked/humiliated, and to those folks, I say godspeed. I'll pass my time with something fucked in a different way, or way more wholesome.