i almost feel bad for mc, his mother abandon him (she explain why later but still), , his "girlfriend" Abbie leaves him as soon as she gets a divorce from her husband (after cheating on him for four years), without giving mc any reason of why she leave or where she goes.
before she leave, she told him to keep countings day until they meet again (if that happen at all) and to rebuild his life in the same sentence, how can he move on after that? and soon after that his father dies in front of his eyes .
and as if that wasn't enough, she put another nail later by sending him a text to tell him she's expecting his child (which he won't be able to see since she's already left...)
I don't really understand Mc's reaction either, he's supposed to love Abbie, she leaves him without explaining anything and he doesn't even try to find out her reasons (he just ask if it's because of her husband, she said no but doesnt push it further) or to hold her back, he just accepts it...
And with how dark the story seem to be, i wouldn't be surprised if mc was just Abbie toy to help her bear with an unhappy marriage...
Even though it doesnt look like it and she appears to be a sweet and caring person, some people can be very good at playing with other people's feelings and hiding their true nature, and her lying and hiding a lot of things doesnt help to trust her if/when she reappear in the story.