Why would Mina's presence depend on whether MC has sex with her? She is friends with Felicia (and a prominent talent in Felicia's husband's agency) Hana, potentially Edwin and maybe Ian to some extent. She also potentially has Veronica as her personal trainer, and at the current end of the game she also knows Rose.So if you choose HanaGF, does Mina just leave the story or what?
Maybe let's not focus so much on MC's dick, neither he nor his appendage are the center of this universe.