The MC did indeed prove it, but so far the girls haven't. Sometimes it feels like only the MC is willing to put in the effort to make things work between him and his chosen girl. This is most explicit with Sage and Bella. Neither Sage nor Bella have done anything thus far to prove that they would fight to have a relationship with the MC. Sage still sees the MC as fuckbuddies and Bella is still scared to get into a relationship with the MC even though she knows she has feelings for him. As things stand, I'm more of a believer in a breakup than an outpouring of love from an MG until Ep.12.
Josy and Maya date MC despite knowing how troublesome such a relationship can be, add Maya's issues to the mix and they're all perfectly aware it'll not be easy.
Jill puts up with a dumbass blackmail plot to help MC even if they're not really dating, despite how much shit people over here give her, the girl has shown she won't just fuck off the moment something's giving her trouble.
Both MC and Bella are mostly aware of how much shit they're in for if people find out and still they decide to date each other, what else do you want them to do to prove to each other they're serious?
And Sage has poured her heart out for MC, he knows how difficult the Chad situation was for her or how hard it was for her to ask her parents for help, and has shown to MC that she's interested and won't give up on him that easily. He knows she's not a basic bitch who dumps people like nothing.
If you don't think that's enough then I maintain what I said, you give them too little credit.
The example you gave of Sage especially, I find extremely ridiculous, if she dumped MC because he rejects threesomes or some other bucket list bullshit like that, she'd drop right down to the bottom of my LI tier list, what a stupid fucking reason to break up with someone you care about
![KEK :KEK: :KEK:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)