My ex wife is leaving town with my son without the fathers approval. My son and I are extremely close and he is upset as well as myself. Our hole separation has been a mutual agreement I have given money when ever she has asked and have had my son 50% of the time. Can this be done? Can I do something to stop this from happening?

Are you the father? Because the way you worded it, there is room for doubt. ("... without the father's approval. ..." - Why not just say "... without my approval"?)

Sure. Sue her in court for a shared custody schedule and prohibiting her from taking the child more than so many miles away.

If there is court ordered custody and visitation? If there is, then she can't move if it affects the visitation schedule. The father can file in court to prevent the move. At least until a new visitation schedule can be arrived at.

If there is no court orders, then the father should immediately file for custody and visitation.