I don't know T. I guess some of them just develop a fixation on someone for some reason, and their feelings towards that person, whether good or bad seem to intensify so that they can't back off.
I don't see you as the stalking type Watson. You've got a caring disposition. People who DO do it, don't seem to care that it might bother their victims, or maybe they don't see it like that, I don't know.
I know, but they're often sad cases who can't form decent relationships with women. Then their fantasies become fixations, but I don't think that all stalkers mean to frighten their victims. Sometimes they might have an overwhelming attraction to someone, and don't seem to realise that following or watching them's taking things too far.
It'd be better for them to learn to approach people in a proper and friendly way, not to do anything to frighten them - but some men're actually scared of women and so build up fixations - and stalk them.