There was a young couple that we knew who got married.  But not too long after being married the guy started messing around with another woman.  At one point he even left his wife to pursue this affair.  That summer a  group of us gathered around her and prayed.  We prayed for her, we prayed for him and we prayed for their marriage.  It wasn't long after this that the guy came to his senses and cut off the affair.  Then he came back to his wife and asked her to forgive him.  She forgave him and then they slowly started to rebuild their relationship.  Eventually, they were completely reconciled and now they have a happy marriage together.  I feel like our prayers played a part in the healing of this young couples marriage.