I identify as straight, but I have tried dating a couple of guys before. It was okay, but the sexual interest was rather lacking, hence my identifying as straight.
I would have no reservations about dating a bisexual girl. It might make me more comfortable, in fact, because she might be more open to dating me if I do decide I would like to do some different things with my body, and possibly become female. Not that I would assume it to be okay, but generally that's a good sign of a bit of open-mindedness to that sort of thing, which would be rather nice, if not necessarily something I need.
If a lesbian were a good and trusted friend of mine, and decided to encourage me to transition and become female, and also wanted to date me, I might feasibly be interested, at least passingly.... ^^;
As for TG, I will divide that into various separate cases. I would date a female whom identifies as male or androgynous, but sees no need to alter his/her body. I would also date a male whom identifies as female, if she took hormones and looked reasonably okay as a girl, regardless of op-status.
I might feasibly also date a male identifying as androgynous, though it would still be mostly an experiment as per what I mentioned up at the top. Female-like curviness tends to increase my interest, even in a male, so a male whom identifies as androgynous and takes estrogen may be of interest to me. Never encountered such, but it's possible.
As for what it means to "identify as androgynous", that's a little different from not caring at all in this case, and generally means the person does take some active interest in being an "in-between" sort of gender.
I would have no interest in someone who identifies as "neutrois", or non-gendered, and actively tries to remove his/her gendered physical traits (which is different than having some of both, like an androgyne).
Also, just because I know what all of these are supposed to be does not mean I know why they do the things they do. Don't ask me about the motivations of a neutrois, or how it's that different from an androgyne. I don't really know very well, but I don't tend to like it.
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