Are you open to replacing the mantel?

I thought of that buty husband built this one do o need to try to use it. He thinks wrap around wood trim between the stone and the mantel would work but I can't picture that.

Perfect opportunity to add a fireplace to the master bedroom (if there isn't one there already). Build a fireplace that this mantle will properly fit, and then your husband can build a new mantel for this fireplace that will go across the full length of the stone.

The mantle is too short.