I think the abrupt feeling comes from the fact that the smack from chapter 28 felt more impactful than the resolution. Like for the most part, this series is a pretty chill exploration of individuality while still in the structure of a, now recommitted, marriage, so that moment kind of jumps out in contrast. I actually had to reread the chapters in between that and the ending to recall that they have kissed on page without issue since.
Overall, it's a cute series that falls in line with this particular author liking to explore ace spectrum style relationships while still offering a different approach to it than their prior work. It's not gonna be everyone's jam, particularly if you're the sort frustrated with how mainstream media typically neuters same sex relationships ("and they were roommates" or "it's up to interpretation" are go to statements for a reason). But a genuine read through will show you that's not really the intent or even the impact here.