Books to understand the facinating psicology behind the human brain of a stalker

More specifically how someone who is obssesed with something/someone. I want to find a good book about either someone who is so obssesed with the thing there obssesed with it consumes them or the process behind being completely obssesed with someone they can't have. The person is for example, a celebrity who hasn't ever even given them a glimpse of hope but still they stalk and obsess over them. Not even when they are turned down multiple times they stop. Is it some childhood trauma that affects the way they think? Is it the celebrity who shines to much for their own good? Or is it the fact that they will forever chase and crave what they cant have?What makes people so obssesed? Do you know any book similar to this? Thank you:)
Honestly, if theres any horror/thriller books like this I'd love to read them too.