I think some people are putting too much emphasis on Asumi's goal of finding Mai through having sex with a bunch of other women... Like don't get me wrong, consensual non-monogamy would be cool, but this isn't exactly typical romantic development (Asumi is not chasing Mai because she's madly in love with her). From a storytelling perspective, finding Mai is primarily an excuse for Asumi's lesbian brothel adventures, not the main point of the story.
I feel that finding Mai still is the primary goal for Asumi as a character if nothing else then so that she could find closure and be able to move on. It is also very conveniently a catalyst for the brothel adventures, but I definitely feel that it is still the "main goal" for now.
I also don't get the criticism that these chapters are straying too far from the premise. Why is it a bad thing that Asumi found someone she wants to do it with without paying for it? Was she supposed to limit herself to buying sex for the whole series? And both her and Nanao's experience with paid-for sex gave them a bit of extra courage to cross the line with each other, so the development is not random at all. I for one can't wait to see where it all goes, regardless of which ship (if any) sails in the end.
Heads up to folks mentioning Mai and the direction of the series or lack thereof, do remember that in chapter 16 Asumi directly told Nanao about her brothel escapades and the reason for them. I feel that, at the very least, the way the story has been set up and developed up until now has been more or less intentional.
It doesn't align with me entirely, but I do like this take.