One Small Hitch (2013)

On a flight home to Chicago for a family wedding, childhood friends Josh and Molly innocently agree to fake a wedding engagement to make Josh's dying father happy. Things quickly get out of hand with their two boisterous families, and a series of events causes them to pretend to be a couple and start planning a phony wedding. When the playacting begins to foster real feelings, the two must make some serious decisions: Split up and return to their lives in LA, or make a life as a couple back in Chicago?