Why do good guys treat me badly?

I stay single for most of my life because I don’t want to date guys that are assholes, flashy egos, etc…but when I finally find a good, sweet, nice guy, they treat me badly. Good and smart guys with good relationships with their families, good heads on their shoulders… They welcome my affection for a few weeks and make me think we have something special growing until one day they break the news to me that they don’t see me in a romantic way, even though they just did so many romantic and intimate things for me. and its like a switch went off, they suddenly have no more interest in being touched or held by me and nothing I can say or do can get to them, like they just went cold… they even said the cruelest things to me after I was pretty desperate to get an answer or explanation for that behavior..

But the assholes are the ones that want me..guys that cant form an emotion more than hungry angry and horny, want me, but I don‘t date them because I like to think that I’m smart and know that wouldnt be a good experience. (not to mention I’m not even attracted to that anyways).

So what is it? Why do good guys treat me like crap and why are the assholes the only ones that want to pursue me?