What is the solution that would please God and end the confusion between leaving my fiancée or changing my place of residence far from my mother, knowing that the reason for this confusion is my inability to find an apartment for rent near my mother despite the long engagement period?

The matter is easy. As long as the marriage contract has not been concluded, there is no injustice to the fiancée in leaving her. The engagement is a promise that is commendable to fulfill, but not obligatory, especially if her conditions are restrictive. If the choice is between staying with your fiancée and abandoning your mother, then it is obligatory for you to leave your fiancée, because obedience to your mother and her satisfaction take precedence. May Allah compensate you with someone better than her. Do not despair of convincing your fiancée, and do not rush to break off the engagement if she is a woman of good character and religious devotion.