My One and Only by Kristan Higgins

Divorce attorney Harper James can't catch a break. Bad enough that she runs into her ex-hubby, Nick, at her sister's destination wedding, but now, by a cruel twist of fate, she's being forced to make a cross-country road trip with him. And her almost-fiancé back at home is not likely to be sympathetic.

Harper can't help that Nick has come blazing back into her life in all of his frustratingly appealing, gorgeous architect glory. But in Nick's eyes, Harper's always been the one. If they can only get it right this time, forever might be waiting—just around the bend.