I would remove the lesbian tag. It doesn't matter if she is a lesbian there is no lesbian sex and people looking for Lesbian sex will be disappointed. Also if she's banging a guy she's not lesbian she's Bisexual.
Situation-ships like this are becoming a lot of common (albeit low key) than most realize. It's weird, but there are self certified lesbians (who are secretly bi) that would go for some side "D" every so often, typically after a break up, a lengthy dry spell, out of boredom, or curiosity...but usually only with a man they know well enough...This also explains why so many of them get pregnant and have to explain to their gf's/wives why...