This is a perfectly normal representation of a healthy and mentally stable lesbian relationship with no abuse or manipulation at all, clearly.
In all seriousness though, I have some major issues with this already. Firstly, for a supposed romantic comedy, this wasn't very funny nor romantic. Honestly, it was more creepy than anything else. Both of these girls are unhinged in different ways. The little sister essentially offering to 'sell' her body in order to get with her sister is pretty messed up, and the fact that the gyaru so willingly jumped on helping her after being offered sexual favors is also not a great look. I can only see this ending badly.
I honestly want the older sister to be completely straight and to get grossed out if she ever finds out about her little sister's feelings. Or for her to either already have a guy she likes or is going out with secretly.