Why would a man refuse a divorce from a wife that doesn't want anything to do with him?
You would have to ask him why.
If she is more "property", well... she needs to find someone who will appreciate her.
If its more of a religious reason (his or their religion is against divorce), thats a bit trickier. We dont want someone thinking they are going to their religions version of Hell if they get a divorce.
But, there are ways to get that divorce without his signature. Talk with a legal aid, or a lawyer, or maybe your priest, rabbi, minister or similar.