It's hard to say, without knowing you, or your partners.

I can say that it is very possible to have a string of bad luck, when having romantic partners. I can also say that it does NOT mean, in any way, that you are not good enough, that you are too old, or any of those things.

I would advise writing down a list of traits that each of your partners had, and finding commonalities. I would then write down a list of things that you do in those relationships, and think about whyyou are doing those things. What do you want out of a relationship? What are the traits you have been seeking in a partner?

Are they perhaps not in line with what you really want?

I would start there, and establish a baseline for yourself. I would strongly advise not seeking a new partner until you do this, as it might hurt you more.

Please remember: you ARE good enough, and you ARE valid. Relationships of any kind are messy. I'm happy to help as I can, but a lot of this is something that is in your head, and thus, only you can do.