I'm typically okay with reading about toxic relationships, but their relationship is painted in a positive light especially in later books with

Travis' brothers wanting a relationship like theirs. It's their ideal despite how toxic both characters are to each other, more so Travis than Abby. Abby makes a few comparisons between her emotionally abusive, heavy gambler father and Travis, pointing out how alike they are but... still choosing to stick with Travis, which made their relationship unlikable for me.

Travis also has violent tendencies such as

trashing his entire room and practically most of his apartment because Abby won't see him anymore.

I also don't understand how Travis has a six-pack when we never ever learn about his work-out routine, and I believe he said once that he doesn't go to the gym at all.

Yeah. The book wasn't for me.