Finding the perfect match can be difficult, especially if you're a casting director. Although Cameron Diaz and Jason Segel don't seem too mis-matched, "Sex Tape" still got us thinking about some of the most unbelievable pairings in romantic comedies from recent years. Some duos fail the crucial chemistry test, while others are just a little too May-December for their own good. Our list even includes a film that is clearly not a romantic comedy, but the couple is so outrageously unrealistic that we couldn't resist.

Check out our list below. Do you agree with our choices? Who would you add?