10. Jennifer Lopez & Ben Affleck (GIGLI)
Not the most shinning moment for J-Lo and Affleck, with the then-couple starring as the hit-man and the lesbian that become best friends. Their on-screen roles granted them about as much success as their marriage.
9. Jennifer Lopez & Ralph Fiennes (MAID IN MANHATTAN)
Holy No Chemistry Batman! J-Lo makes the list again, this time paired up with an awkward Ralph Fiennes, in a movie that could just as well not have been “maid”…
8. Nikki Blonsky & Zac Efron (HAIRSPRAY)
Nothing could ever top the raunchy genius of John Waters’ original “Hairspray” starring Ricki Lake as Tracy Turnblad- but this version casting the young heartthrob Zac Efron of Nikki Blonsky’s affections makes for a rather atypical duo that don’t quite cut it in the realms of on-screen romance.
7. Julia Roberts & Woody Allen (EVERYONE SAYS I LOVE YOU)
What a lucky guy that Woody Allen; he sure gets together with some of the most gorgeous women in Hollywood. Maybe the fact he’s the writer, director and main star of most of his movies has something to do with it. For what it’s worth, Allen is still one of Cinema’s greatest talents, so whoever he matches himself up with, at least he’s always charming.
6. Kate Winslet & Jack Black (THE HOLIDAY)
It is mostly just difficult to take Jack Black seriously in a romantic role is hard enough. Pair him up with Kate Winslet, and you’ve just produced mismatching at it’s best.
5. Anne Heche & Harrison Ford (SIX DAYS SEVEN NIGHTS)
Quinn (Ford) and Robin (Heche) try and evade pirates and the outcome is… not so sexy.
4. Adam Sandler & Kevin James (I NOW PRONOUNCE YOU CHUCK & LARRY)
When two straight Brooklyn firefighters pretend to be a gay couple, you have pretty well made yourself the worst match of the century.
3. Katherine Heigl & Seth Rogen (KNOCKED UP)
A one-night stand ends up having these two mismatched stars, raising a baby nine months later.
2. Charlize Theron & Woody Allen (CURSE OF THE JADE SCORPION)
Woody “Cassanova” Allen strikes again in the film where two people who hate each other, end up realizing, maybe they don’t. Entertaining movie; really unlikely match.
1. Jessica Alba & Mike Myers (THE LOVE GURU)
Mike Myers tests his Mojo in the “Love Guru”, but really now, would a hottie like Jessica fall for a Guru like Maurice Pitka?
Source: http://www.hollywoodtoday.net/2009/02/14/hollywood-valentine%E2%80%99s-top-10-most-mismatched-movie-couples/