All guys in this manga are shit except the father and that one died :/

So he blackmailed her because she said no, what a valid reason! The brother is a pimp and the ML was a manipulative asshole, who used her father's health and her brother's sexual orientation to force her to have sex with him, prime male material right there. Imagine that she had a brain and didn't like him, he would have done the same... That's harlequin consent folks