Istikhara is not for your whole life! It is for the marriage to go ahead with it or not! The decision was good to marry that particular person! However, what comes afterwards is your own fault whether you didn’t manage this relationship well or you didn’t base your choice on what pleases Allah. For example, a drunkard proposes to you and you pray istikhara and you go ahead and marry him! Istikhara was wrong in the first place to be performed!