Stipulating not to marry again but having to do so later

Q: I married a woman six years ago. Since she was an orphan, well-mannered, kind, and easy to get along with, I promised her not to marry again except in three cases: death, divorce, or physical disability. As time passed, she became prosperous and she now owns houses, a farm, and other properties. However, our marriage has suffered and our relationship is not the same. She refused to move to my house, because I no longer feel comfortable and calm in hers. Until now, she has not given birth to children. I am thinking of marrying another woman. She has no objection to that but I do not know how to deal with the promise I made to her. On the other hand, if I did not think of marriage once again, my wife is not young and she is unable to give me the basic rights as a husband. Kindly, give me your Fatwa in this regard.

A: If the case is as you mentioned, that her conditions have changed from the time when you made your pledge, and that she does not object to your breaking that pledge, you are permitted to marry again while she is still your wife, but you must offer Kaffarah (expiation) for breaking the oath. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.