Poor Nanao continues just get flat out used by the scum that is Asumi
It’s entirely her own fault. She was the one who was too cowardly and set the terms of their relationship. Asumi is just doing what Nanao said she wanted.
Also, we already know Asumi doesn't want a committed relationship with Nanao. It's up to Nanao to decide whether she's okay with having a fwb relationship with someone she has a crush on. She said she was, and honestly, she doesn't seem to hate the arrangement.
One thing that bothers me about a lot of comments in the same vein as the one you replied to is that they feel like they come from the angle of "Nanao has feelings for her, so Asumi should reciprocate". That's not how romantic attraction works, even if a lot of people seem to think that way (toward real-life women too). And if the angle of the comments is instead "if they're not dating, they shouldn't have sex", then... I guess people missed the point of the story ?