But Nanao's still not being 100% honest, probably not even with herself, proposing the FWB arrangement when what she really wants is true love forever, and then acting like Asumi agreed to true love forever instead of FWB with how she's treating her.
When did she act like that tho? They're friends with benefits and they fuck that's the extent of their relationship right now, nanao is not asking anything out of asumi, she's free to do whatever she wants with her free time, asumi spends time with nanao out her will
Fundamentally, Nanao wants to possess Asumi. Even right from the start of her feelings, remember how she stalked her and saw her entering the love hotel with a woman, which is how she got the idea that Asumi worked for the brothel to begin with? Asumi, however, does not want to be possessed. This is a fundamental gap between them that is irreconcilable without Nanao coming to terms with it and realizing she can't have what she wants.
You're making nanao intentions and actions look way more heinous that they actually are, from her point of view her friend seemed in desperately need of money to the point of having several jobs at the same time, she was genuinely concerned about her situation. Also let's not forget that asumi was the one that invited nanao to the hotel after the date ended, nanao was perfectly fine with letting asumi go after that.
Asumi is interested in nanao that's just a fact, and the idea that she's manipulating her or that she sneakily dragged her into a relationship is just ridiculous, cuz again it was asumi that invited nanao to the hotel and accepted being friends with benefits after that