I have no feelings!! 🙈🙊

Okay so I've had this thing basically my whole life, where I'll like a guy when I first meet him and we'll flirt and hang out a lot and then right when it starts to get serious, all of my feelings towards them disappear(I usually end up dating them anyway). Longest I dated was 2.5 years, then 1 year, then 6 months(all three of them proposed). Anyway I'm not sure why I can't get myself to actually want to be in a relationship or actually care about someone. I'm an emotionless blob. Is it just me?? What can I do? Help! 😔