I'm glad that you are getting good and biblical counsel Evan. I pray that God will guide you through restoration with Him and possibly with your wife.
I'd guess that when Lutzer says that divorce is the only option in persistent abuse, he is addressing the cases that I've dealt with - physical abuse. Being called to a friend's house by her 5 year old son because his father just beat his mother into almost unconsciousness...again. Her jaw was broken, her arm was broken, the 3 children were cowering in the closet. The police were there and my friend was being tended to by paramedics. In this case, I helped her as she went through the divorce. It was for her safety and her children's safety. Her husband was just that unsafe. It's been 12 years and she is still single because she feels that biblically she should not be married again. She found her feet and her voice and is now an advocate for abused wives and her children walk with the Lord. I don't think Lutzer was addressing being unhappy but actual physical abuse.