I'm in a fault state, but my L said most judges will not allow children to move out of state if the other parent is actively involved, regardless of how the marriage ended.
I worked with WS to move about 1.5 hours away. At the time, he agreed to move closer to me (and the kids), but...of course...he hasn't. No biggie, I'm used to being a full time single Mom now. He sees them e/o weekend. He traveled about 50% of the time.
I wanted to move to the same town as my mom, which would have been 3.5 hours away, and EX refused. So we compromised on 1.5 hours away. I am now in the middle between ex and my mother.
If you are still in the negotiation stage, then make relocation part of the negotiation process. If you can't afford to live where you are, then you need to negotiate more spousal support (or other financial support) or convince him it is in the best interest for all of you to relocate to a more affordable area.