Have we ever cracked the code how blue pulled betas can get decent girls?

I know a guy whose in a relationship with a decent girl and he’s very temperamental. Worst than a female. Constant mood changes , always depressed, suicidal, shows extreme jealously towards all guys who are better than him in anyway, no job, not in school.

Yet this HB7 will defend him till the end and is always orbiting him! He is part of one of my plates friend group so I have to be around him time to time and he always makes remarks to get under my skin, which ignore cuz he’s like 5’3 and just a unattractive guy. But when this happen she hops on with him.

Anyway why would a decent HB7 girl want that? It goes against all TRP principles and he is as beta as they come, yet she’s still attracted to him? Someone explain?