It depends.
If there are children involved?
Then in many cases the “immoral” decision is a person (man or woman) who is trying to break up a home and thereby significantly impacting the children that he or she brought into the world.
If there are no such factors, then I do not know if it is “cruel”, there really are very very rare cases where the husband refuses to give a get simply for “spite”. (I am aware of several cases, none of them were cases where the husband was refusing to give a get simply for “spite”.)