You, Me and Dupree (2006)

After standing in as best man for his longtime friend Carl Petersen, Randy Dupree loses his job, becomes a barfly and attaches himself to the newlywed couple almost permanently -- as their houseguest. But the longer Dupree camps out on their couch, the closer he gets to Carl's bride, Molly, leaving the frustrated groom wondering when his pal will be moving out.