Bisexual person in a relationship with someone of a different sex: I'm not straight, I'm bisexual
Gay community: you're only saying that because you want to be a part of the Gay Club, you don't belong with us, you're basically just a straight person anyway
Bisexual person in a relationship with someone of the same sex: I'm not gay I'm bisexual
Gay community: why do you feel the need to clarify that? You just want to be one of the straight people, you just want to reassure them that you're Not That Gay, you don't belong with us

Sweet mother of God.