That was my thought exactly. According to all the arguments I've heard, homosexuality is not a choice. So one couldn't arbitrarily decide that she is no longer a lesbian.
Talk to Elen Degeneres' ex...
And what of those "bi-curious" ads? Sounds like they want people to experiment with something that "may not be their lifestyle".
Certainly for some people it is a choice.
Bi-sexuals certainly have to make a "choice" of male or female when they become monogamous (no polygamy, even in the homosexual agenda for same sex marriages at this point).
Actually, one of the funniest scenes I have witnessed was when lesbian activists protested against a male homosexual activist who was giving a speech about how he didn't choose his sexual preference.
Evidently, this is quite a debate in many homosexual groups. Many lesbians claim to make a concious choice to shun men for feminist reasons. I also think the appearance of AIDS in the early 80s stopped many men from claiming it was a choice.