DAE get triggered by unreliability and a general lack of attention?

This triggers me so badly and I'm not even sure why. My mum was a bit like this maybe. She would make promises and then forget about it or never talk about it again. On the other hand, she always picked me up reliably and remembered things that mothers remember, such as my birthday, etc. (My father probably doesn't even know exactly when my birthday is.) Anyway, my soon to be ex-partner is the same. He doesn't think things through, forgets stuff that's important to me and let's me do all the planning. How do I get rid of this pattern? I want to have a normal relationship and not feel like a child being let down all the time...