One Small Hitch (2013) on Netflix

Molly Mahoney (Aubrey Dollar) is flying home to Chicago for her mom's wedding... bringing a "Mystery Man" with her, but when she discovers this Mystery Man has a Mystery Wife, she dumps him at the curbside check-in. She ends up crying on the shoulder of childhood friend Josh Shiffman (Shane McRae), who is flying home for the same wedding. Emotionally drained, Molly passes out in Josh's arms just as he gets a phone call from his parents. Josh learns that his father is dying and his only regret is that he will not get to meet the woman who will one day become his son's wife. Desperate to fulfill his dad's final wish, Josh claims he has already met that woman... close family friend: Molly Mahoney. When Josh sheepishly confesses his ruse in mid-flight Molly is furious, making him promise to right the wrong the moment they land. Only when they arrive - it's too late! Word has leaked out and they are swarmed at the airport by BOTH FAMILIES with well wishes and congratulatory banners. Molly's family is delighted that her "Mystery Man" turns out to be Josh, and Josh's dad is thrilled that his Playboy son is finally settling down with a nice girl they've known all their lives. Josh convinces Molly to play fiancée by using a deadly combination her Catholic Guilt and his Playboy Charm. But as they plan their phony wedding... the two of them start to fall in love for real. This turns their dating lives, and family's interactions hilariously upside down tugging on every heartstring in the process.