Is it normal to be like this?

Ok idk whats wrong with me i dont even know how to explain this but when I like a guy I usually fall hard. And not like OMG i want to stalk you and blablabla. But like I wont flirt with anyone else.. Im loyal I guess even with out a "title". But anyways usually after I break up with someone or stop seeing them, I feel like its a load off my back and I just start thinking of every thing they've done or said and I get really really turned off and grossed out and embarrassed. And i regret even liking them or spending time with them or having sex with them. I still remain friends for the most part or civil at least but, why do I do that? IIN?