This. So much of this.
I have two friends that I thought I was just buddies with that I've had to cut out of my life because they continue to flirt with me... and they're not gay. It makes me uncomfortable because it's painfully obvious that they don't see me as a man, and because I just don't see them that way or have any desire to.
Don't get me wrong, I can date guys. Its strange because emotionally, I'm pretty sure I'm pansexual. But when it boils down to the physical (and it always does with most people my age) I just can't with another man. Its bordering on a repulsion towards the male genitalia (on another person). That might change after my transition when I feel like I'm secure in my masculinity, or something like that.
Sorry, got off topic there.
Its just really, really, really sucky when a random guy flirts with me. Because I know he's not looking at me as another guy. Basically it just reminds me that I'm not passing, and that I still look enough like a girl to be at least mildly attractive as one. And then I get really conscious of the fact that I'm not passing, and I start fidgeting under my binder and worrying about everything.
On the whole "girlfriend" thing: totally 100% get that. Its enough to make me not want to leave my room for a week. A girl I was dating a while back (and a transwoman none-the-less (still closeted about trans, presenting male, out to me for obvious reasons)) slipped while she was on the computer with her gamer friends and I was in the room. It would have been understandable if she had known me as a girl first- but she had always really known me as Dustin. That right there spoke volumes to me- that either she was embarrassed to tell them and didn't want them to think she was even a gay man, or that she just never *really* was able to see me as a guy. Either way, it made me very iffy to her for a few weeks, even after I confronted her about it right there, and she later corrected herself to her friends. When that word is used towards me, it makes me very edgy.
Also this one time in Iraq: I was hanging out with one of my friends from another shop (apparently too much), and every time I would walk into his office area (often because our shops worked together in a way) one of his co-workers would say (jokingly, but still) "hey xxx, your girlfriend is here." Good lord, did that drive me up the walls- for more reasons than one. Didn't help that I couldn't correct them about the girl part; thank you, nails holding the closet door shut.
Anyway- I feel like its probably a pretty common feeling to have dysphoria triggered by that.