Better With You (movie, 2010)

Maddie and Ben have been dating for nine years and they know each other inside and out. Maddie's younger sister, Mia, has been dating Casey for seven weeks. With a shared c'est la vie attitude, Mia and Casey announce they're getting married and having a baby. It's news that throws Maddie for a loop. Surprisingly, the girls' parents, who have recently adopted a carpe diem sort of philosophy, couldn't be more pleased.