I am aware of marriages that have recovered from affairs, alcohol, addiction, abuse, and just general unhappiness. We have our own testimony of a marriage restored after 16 months of separation. The key to these recovered marriages is that at some point one partner or the other chose not to give up in spite of an apparently hopeless situation.
Jesus talked about the woman who sold all she had to find the pearl of great price. He also promised that he who seeks, finds. If you are in a bad situation in your marriage my encouragement is to ask God for help to never give up and then ask for His help as you start digging for answers. Dig in His Word, dig in this blog, dig on the internet, dig in conversations with reconciled marriages, dig in books, but just determine not to give up.