My own theory is that whatever Rhys’s sexual orientation— gay, straight, or bi— its ultimately been so warped by his exposure to porn and paraphilia during adolescence that even he can’t decypher it. Add in the possible botched dick surgery and his inherent personality disorders, and you have one very angry man who seems deeply confused and frustrated by his own sexuality. He certainly doesn’t appear to see sex as either a pleasurable diversion or an expression of love and intimacy but rather as a means for exerting control over others (the shit with his ex).
Even a thirsty exhibitionist like Zach is at least capable of expressing some erotic joy when it comes to his deviancy, even if most of the time it is just for show.
Now this is totally anecdotal, but some of the closet case types I’ve encountered have had a certain penchant for strong, even slightly masculine or butch women— most of whom are straight. In two of those cases the closeted guy eventually trooned out. Rhys’s ex wife is not a butch lez, but she does eskew conventions of femininity with her build, her tattoos, and love for powerlifting. And here’s Rhys on two women he’s claimed to have dated;

A boxer and a prison guard. Now this may just be Rhys flexxing his lesbian bonafides (lol @ diesel) but it could also tie into
@heathercho ’s idea of Rhys sexuality in part being tied to dominating “strong” women.