My 3 year old son's mother and I split up long ago when he was only about 6 months old. We have a good co-parenting relationship, and we're at peace with each other.
I started dating last year. My son really liked her, but we broke up after about 6 months. During the time we were together, she was a large part of my son's and my life.
For quite a while, my son would not ask about her at all; all of a sudden, every time I get my son, he is asking if we're going to [Ex's name]'s house today, where I just try to reply that we aren't together anymore, so no. We broke up about 7 months ago, and this behaviour just started happening a few weeks ago.
The horrible falling out involves the child she gave birth to, as it's actually not mine. I am not interested in trying to restore that relationship, and neither is she. I would not want my son to completely forget her, as she was a good step-parent for the time she was around, but I feel like I'm breaking his heart by saying we aren't together. What can I do to help him move on?