The two decided to get a divorce. Did they ask God's advice on this? (Rhetorical question). Of course it can be mended. With God all things are possible, but are they doing things God's way or their way. God has a plan for their lives, but they may not be interested in that, and just want to follow their own plans. Maybe they haven't looked at it this way at all. Obviously they both want change, as does God, but how to go about those changes and what changes to make is the issue.
Father, I pray that these two will humble themselves before You and Your will for them. That they would put You, instead of themselves first, and receive Your blessing; a blessed marriage, a blessed love, and a blessed life and future. Amen.