In my case, I am infamous among my friends for always saying no whenever I am asked out. I don't think I've ever said yes in my entire life. So disclosure and dating are non issues for me because I'm just not interested. And that fact may greatly impact my opinion. But it seems to me that all three of the options in the survey apply. Yes, it's prejudice. Yes, there are differences. And yes, there are other things entirely.
Prejudice
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When you say "transgender" to people, many people think of men walking around in dresses. They don't understand the difference. What matters to them is that they think a transgender woman is a guy. And they aren't interested in dating a guy.
People often believe that transgender people are mentally unstable or defective in some way. Who wants to date someone like that?
People often believe that trans women are sex workers and fetishists. There have been issues with dating sites kicking off identified trans women and giving fetishism as an explanation (that's right,
match.com, I'm looking at you).
And as has been pointed out by another poster, dating a trans* person means getting hit by some transphobic prejudice oneself.
Differences
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There are often physical gender nonconformities. For example, height. Guys often don't seem to like dating someone taller than them. Or voices. A lot of people find a deep voice coming from a person who looks female to be very jarring and disconcerting and a lot of trans women do have deeper voices.
And there's behavior too. Old habits die hard for most trans women. For example, a couple of months ago I was at a trans* group meeting. Two trans women arrived at the same time as I did. One got to the door first and opened it, then turned to the other two of us and said "after you, ladies." The second one turned to me and motioned me to go on in. Then when we got in, there were not enough seats. A trans woman went and got me a chair, carried it in, and unfolded it for me. Then at the end of the meeting, I started to put the chair back (I saw where it came from) but yet another trans woman took it away from me and put it away for me. This interaction was a little bit jarring and confusing for me because it felt--with apologies, and for lack of a better word--gentlemanly. Even though it was women involved. Like I said, old habits die hard and most people have some left over ones.
Dating roles are very gendered. So imagine how jarring it could be if you're visibly accustomed to playing the role that the other person is trying to play. And imagine if the other person is unaccustomed to dealing with people who are adjusting to a different gender role.
Other things
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People are very hung up on labels. If you believe that trans women are men (see above under prejudice) then what does it mean for you if you are attracted to one? Does that make you gay? It's amazing how many people ask that. And how upset they are about it.
And there's also the fact that people do sometimes want genetic children. So they won't date anyone who is sterile, whether cis or trans*.
And there's also the reality of different strokes for different folks. A lot of people may be attracted to blondes, but not brunettes. And they may be attracted to cis women but not trans women.
We also have a habit of stigmatizing people who are attracted to trans* women too. It seems like a lot of trans women automatically label anyone attracted to them as a ->-bleeped-<-. Even the ones who don't go all fetishistic. It's like trans women think poorly of anyone who might find them attractive. And that's a shame.
And of course, the reality that if you are older, then guys tend to lose interest.
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All in all, things may look depressing for a lot of trans* people looking for love in cisgender places Many do end up in relationships with other trans* people.
But there is hope. Things seem to improve the younger people get. And my best trans* friend had one of the most loving relationships I've ever seen with a cisguy. They are both in their 60s, so not exactly young. So there are people out there even in older demographics. There is love to be found. You just have to keep digging.
Being trans* adds some extra difficulties. But the need to keep digging for a long time is not unique to trans* people. I think that's how it is for most people.