And I do agree, but I feel they're moving too fast.
Remember the peer pressure angle? When that was supposed to be the reason that she was hesitant to go into that relationship? They resolved that in record time: By forgetting it was a thing. Sucks, but these two are at least cute together, so in the end, it is what it is really, just feels so fast, and in a sense, a bit anti-climactic. I do wonder where they'll go from here though?
well - she's yet to resolve the cheating thing. So I imagine that will be a "big" plot point (or whatever counts as "big" in this title, given the speed/efficiency you highlighted).
And barring Yui, it would seem her friend group is very superficial, so there might be some time spent on dealing with that. And the fact that her new almost-girlfriend also knows her little sister's girlfriend and side-stepped that being brought up in this chapter. Dunno if anything will be made of "are our parents okay that both of their daughters are gay" thing, but that's a potential plot point, I guess.
I do agree with how fast it's moving, unless this is all meant to be exposition to set up the story of them going out, and
now we see them deal with the aftermath of her breaking up her "picture perfect relationship" and the potential fallout that results, since she does seem to care at least a little about appearances (though she's self-aware of how she really shouldn't, so maybe it's a matter of inertia more than anything that's kept her in homeostasis up to now).
If it's short, it's short - I admit I'd rather that, than have it be needlessly prolonged by super-forced contrived drama. And like you said, at least they're very cute together.