I highly doubt because you have a disorder has anything to do with this is all honestly.
You just don't feel attached to a character to the degree of OP...Just like many of us here lol.
No, I don't feel attached to fictional characters/settings *at all*. There's a pretty important distinction there, as many times in my life I've been left to feel like an outsider in a group when discussing media because most people CAN do those things. Fiction/fantasy wouldn't be as popular as an overall genre if they couldn't.

Being able to experience love/infatuation for a fictional character is on another level entirely, but even the levels below that are pretty much an enigma to me.