Risque Confessions Series by D.F. Krieger

Keep a journal of your wildest fantasies, but remember the two rules: The fantasies have to involve your spouse, and no reading your spouse's journal. When the marriage therapist recommends this treatment to Hannah and Jason, they doubt the journal's ability to fix Hannah's loneliness or Jason's stress. But as the pages fill with heated longings, they find themselves wanting each other in ways they'd only ever imagined.