Is forsaking one's mother considered a sin if the estrangement is due to an attempt to reconcile with one's wife and calm matters between her and the mother?

The right of the mother is more emphasized than the right of the wife. You must be dutiful to your mother and try to reconcile between her and your wife, because a wife's estrangement from your mother is not good conduct. As for your work in a distant place, it is not permissible if your mother needs your presence and your absence leads to the neglect of her right; otherwise, there is no harm. If the parents are in need of their son's service, it is not permissible for him to depart or neglect them.