Yeah, this manga is the epitome of bitter sweet. The two main characters are each lovable in their own ways, and it's clear that they're both trying their best, but it hurts to see them not quite being able to get there.
Ah it was more about personal introspection, but it's true there is some kind of sadness about not having the same relationship as before. It probably has been mentioned in this post before, but the fact that the relationship will never be the same could be very disconcerting for Mari specifically. I guess it could be hard to have to take the lead after being used to follow all this time.
[...] here really doesn't seem to be any reason why they don't just boink already, [...].
Well, Arisu still have three years of maturity to catch up! Or at least, the time she needed before actually doing it the first time with Mari.
Mari is a bottom it's not like she's suffering not all bottoms wait to be attacked and pushed down some just go with the flow and do whatever to make the other happy if I could go back the the innocent days with my partner it would be like falling in love with her all over again just enjoying each others company and nothing else.