Fireproof  (2008)

In the wake of his daring rescue of a complete stranger, decorated firefighter Caleb Holt (Kirk Cameron) realizes the extent to which he has failed as a husband. In a desperate attempt to save his relationship with his wife, Catherine (Erin Bethea), Holt turns to "The Love Dare," a Christian self-help book. At the prompting of his devout father, John (Harris Malcom) -- and guided by the book itself -- Holt embarks on a 40-day mission to rescue his marriage from the looming specter of divorce.