For some people it is fears and others it is a cluelessness, people freeze up when they have they are afraid and don't know how to proceed and some people don't realize what they have in front of their face until it is too late. As far as long distances, perhaps it is something with someone who thinks in too logically to even consider the possibility of a relationship across oceans and doesn't think of you in the way. Kind of like how someone might not think of you in that way if you were already in a relationship, it might not be because they're not interested or attracted but just don't see it as possibility. You've said you've reached out tho and have been rejected more than once, I don't know how that exactly played out but there is only so much you can do however. I can only really speak for myself but as probably one of the more shier and withdrawn people here all I can suggest is to be open with your thoughts & feelings towards the person and to be reassuring in your interest. Some people have very negative perceptions of themselves and how they assume other people think of them, us on the spectrum often aren't able to read people like NTs do so it is an easy trap to fall into. Speaking of myself again, I almost always assume that most people hate me unless given reason to think otherwise but that's a defense mechanism from a lifetime of peer rejection and bullying which is easier to admit than it actually changing. Everyone is different and how you go about curing that is obviously different too, people have different feelings about relationships and how much they desire them and I think it is very common on the spectrum to reject what has rejected you so previous bad experiences could play part as well.