I need advice

So, I got dumped tonight by this guy I’d been seeing for the past few months. It came completely out of the blue, and his only real reason was that he just didn’t feel that way about me anymore, but up until he brought it up and wanted to talk to break things off, everything seemed completely fine. I know that this is normal, and that this kind of thing just sort of happens in dating a lot, but what bothers me is that I’m starting to sort of see a pattern of this in my love life. This almost exact scenario has played out the last few times I’ve gotten seriously romantically involved with a guy, where things will be getting serious, and then all of a sudden out of nowhere they break things off and their reason is that they just don’t feel that way anymore. It’s incredibly frustrating, and I’m so tired of feeling let down by guys I emotionally let in. In the back of my mind, I can’t help but worry that there’s something I’m doing that drives my partners away, and it’s really getting to my confidence. Anyways, right now I’m feeling very vulnerable and I just don’t know if it’s worth it to let someone in again if the same thing is just going to keep happening in exactly the same way. I know this sounds melodramatic, but I realistically just don’t know if I want to put myself out there to put myself through this all again. Is there something I’m doing wrong that makes this kind of thing keep happening?