I wish the mangaka would've taken time to build the relationship between the old present Neo and the new Maki instead of just jumping to a point where they are already in a relationship...
Or maybe it could've been that him going to the past and changing the future was actually a dream he had while he was in coma (since he later says that he regained his memories after a month).
Either way, their relationship is cute but we're practically in the dark regarding how they got together, how their relationship progressed, how they started living together, etc
Zero Kyori