She’s a beautiful woman, and I don’t understand why Hiromi wouldn’t see her as a love interest.
He was told at the outset that dating was not allowed within the sharehouse. He tried it already with Lili, and it blew up in his face.
I can fully understand him feeling gunshy about doing anything else with any of the other women. Sure, he could move out and then that rule wouldn't apply anymore, but he can't yet, and he's also still in his own head about what he's looking for in a relationship, and until Anju told him
for her, Hiromi had no knowledge of the extent of Tsubasa's feelings for him.
Like, you can think someone's cute or beautiful or sexy or whatever, but that's not exactly what I'd call a solid basis to seeking a relationship, much less in his specific circumstances.
Also I
really don't know if I believe she's just out of the face. Maybe I just don't believe that the author's going to continuously recycle the same motifs from work to work; I'd like to believe she's more versatile than that, and not prone to just making the same story with different names for the parts each time.
But Tsubasa's story isn't exactly over just because she ran away and fell into bed with someone else. If it were, I feel like
that would be an indication of bad writing, not the whole "oh noes my fav got NTR'd" or whatever some readers have been bemoaning of late.