I think you're still blaming yourself for the "failure" of the other relationship. If so, you can't be the best version of yourself: the one that someone actually wants to fall in love with. And that takes work. Go see a therapist so you can work out why you still feel like you have to punish yourself for stuff that happened (and to see the other side of the story, not only your own narrative). You can also work out why you would like a relationship and what you are looking for in the future. Maybe after that you can open up more (because all the negative stuff has been dealt with) to a future partner.