I keep seeing people arguing, so I'll repost this for everyone. Tell me if I'm wrong and we'll talk.

I wonder if you forgot the bonding? An omega isn't in complete control when in heat, so the time that the omega was basically unable to make a rational decision, the alpha bonded with him (of course he was also under the influence but was still more rational than the omega).
The bonding renders an omega incapable of having any other partner and unable to separate from their bonded alpha.Their body will unconsciously ask for their alpha, whether they like it or not, heat or no heat.
As for the child, the omega gave birth to it for god's sake. I'd be amazed if there was no omega who unconsciously came back to see the kid they carried inside their body, or at least thought about how they're doing.
Yes, the omega is selfish and childish, but there is a reason why he acts this way, and it doesn't help that the alpha also has a similar selfish and childish personality. If I remember correctly, this is the alpha's first relationship with an omega; he's usually had alpha partners this whole time. He doesn't know how an omega goes about anything, and the omega never had a partner, much less an alpha, since this whole time he was sure as hell confident that he was an alpha.
This is their first time experiencing all this. And the first mistake made that led us up to this point, was that the alpha, while still able to make a rational decision, thought that he'd be able to calm the omega's FIRST EVER heat by having sex with him. I'll need to reread if I want to give you guys a list of what came afterwards though.
Anyway, they are both at fault and we are bystanders of what is basically two "adults" that haven't gone through puberty at the "proper" time, and weren't able to make the "right" decisions. This is a story of an idiot meeting a closet idiot.