I have the opposite problem than most people, I have always had boyfriends and they get obsessive. I start dating a guy and no matter how he was when we met, by the time he has been with me for a few weeks he is totally clingy, saying "I love you" and talking about marriage, every guy I have dated for more than 3 months has proposed to me.
I have tried to head it off by dating guys who don't settle down (the bad boy/untamed thing I guess you could call it) I've tried telling them up front I have no interest in commitment and considering my personality they aren't gettng a mixed signal (don't know if it is the aspieness or if it is just me but I don't answer my phone, I break plans all the time because i just don't want to leave the house, I am not very touchy feely), I have tried dating casually more than one person (where they are aware of it, I wouldn't cheat) in the hopes that they would take that as a sign we aren't serious, doesn't seem to help. I have had to get 3 restraining orders against ex's who wouldn't take no for an answer when we broke up, and I keep my number unlisted.
The sad thing is these aren't weird or crazy guys when I meet them, they are successful, educated, good looking, independent, all that good stuff. And usually they are the guys that other women complain will never be commited, can't be with one woman ect. No matter what they all end up that way though. My family jokes and says that being with me causes insanity.
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I hate hearing, "you don't seem autistic/aspie". I have a nagging suspicion most people have no idea what autistic or aspie "seem" like in the first place...