8. Rory McIlroy and Caroline Wozniacki: The golfer and tennis player got together two summers ago. McIlroy had just won his first major, and Wozniacki was climbing up the world rankings. Neither has been as good since — but they're still together and just added a family member, a dog.
9. Casey Daigle and Jennie Finch: The former major league pitcher and the former Olympic softball pitcher have had three kids since marrying in 2005. Their oldest is named Ace, of course.
10. Ricky Stenhouse Jr. and Danica Patrick: Both are NASCAR rookie of the year candidates, which you might think would cause friction, but the relationship has been going strong since the drivers announced they were dating earlier this year.
Honorable mention: Matt Treanor (baseball) and Misty May-Treanor (sand volleyball); A.J. Feeley (football) and Heather Mitts (soccer); Curtis Conway (football) and Laila Ali (boxing); Brady Quinn (football) and Alicia Sacramone (gymnastics); Shelden Williams (basketball) and Candace Parker (basketball); Alex Ovechkin (hockey) and Maria Kirilenko (tennis); Hope Solo (soccer) and Jerramy Stevens (football); Andy Murray (tennis) and Laura Robson (tennis); Landry Jones (football) and Whitney Hand (basketball)