Ah yes, I can see that being true. It does especially bite when you put in effort but don't get anything in return. And, once that's happened a couple times, it makes it less likely that you will keep reaching out.

I'm not sure whether you should be concerned or not; certainly it's not the most desirable outcome, and it is regrettable that it's familiar enough to be predictable. I couldn't say whether it's you or not, but there are often many factors that lead to a relationship - of any kind - breaking down, so even if some of it is you, I highly doubt you are solely responsible. And sometimes people just aren't compatible, no matter how much you might wish to be.