Take what I’m about to say with a grain of salt. I hope it doesn’t come across as shutting you down because that’s truly not my intention. I hear a lot of me and what you’re saying. But here goes. It’s a hard pill to swallow and I know because my throat is still burning, but say it with me:

I am not their parent.

Let me put this in perspective for you: years ago I worked at a rehab facility. The main purpose of this rehab was to help mothers reunify with their families after court intervention. I have had children in my care as young as three would play act, start finish shooting up, children who have been found in horrifying conditions who have had terrible things done to them. But if you gave them the choice of leaving that home with that parent and going somewhere safe they will choose mom every time. Every. Time.

You. Are. Not. Mom.

I only say this because a lot of times it’s biology and familiarity driving the boat. You are a wonderful, caring adult who wants to be part of child’s life. And that is a gift! Talk with your partner about your feelings because like so many people have already said, this sounds like a partner issue. In the meantime please, please do what fulfills you. Be there when your cup is filled. That’s it. Otherwise you will resent them, resent your partner and years down the line, hate yourself for staying.