My Maca and GG are both straight. I am bi. I date both of them. GG doesn't choose to date others but would likely be open to the opportunity of sharing a gf with me were it to occur (not a goal, but we have hallened upon the experience and opportunity in years past.
Maca and I, not so much. He dates women and most have been bi. But they arent my type.
So-no I dont really see being bi or straight as relevant.
Additionally I have had threesomes with 2 straight men and i have had them with a lesbian, a straight man and myself, and a bi woman and a straight woman and myself. Just never had a bi or gay man.
"Love As Thou Wilt"