"But the sort of bisexual erasure that takes place when we say 'X can't be lesbian, she's dated men' (or 'X can't be gay, he's dated women') strikes me as pretty unsound..."

"... and not fair to a group that makes up a pretty big chunk of the non-straight population."

Says Eugene Volokh.

And there are also all those non-bisexual gay individuals who dated members of the opposite sex before they became convinced of their homosexuality or even after. People who are not sexually interested in each other may go out together to keep each other company as friends, to deflect rumors that they are homosexual, or for any number of other reasons.