I'm only 5 pages in, but I'm betting this is all because he failed to grow up from being an "edgy teen" before becoming a dad, coupled with the drop in testosterone that probably happened when his son was born.
Some guys seem to struggle with the idea you can't just live your best man-child life when you have kids, you have to put them first. Clearly his reaction to it was to become the complete opposite of what he's supposed to be, to get as far away from the thing that makes his brain feel bad (being a dad) as possible.
That, and he's obviously got nonce tendencies if not will turn out to be one if not watched.