No. Whether the other person is interested or not, due to their sexual preference, that has no bearing on whether or not MY partner is interested in them. And regardless, that behavior is inappropriate to engage in with someone other than your partner while in a relationship, unless both partners have agreed to have an open sexual relationship with others. In my relationship, that's not okay. That would be HIM disrespecting me, and his lesbian friend disrespecting me by allowing or encouraging it. She likes women, so there should be no reason for her to allow such a thing, unless she isn't really a lesbian, and/or she has no disregard for the woman he's with, which is not a friend. A friend doesn't have to like the people in his life, but they do need to show respect for those people BECAUSE of their friendship, especially when it's their friend's partner, they need to respect the relationship. It's inappropriate, end of story, lol, and I wouldn't engage in that kind of behavior with any other man while I'm with my boyfriend, even if that man was gay, because I'd feel like I was crossing a line. So if my guy did that, we would have issues.