When: April 2004 - July 2004

Though never married, Kevin Federline and actress Shar Jackson were in a serious relationship for a few years. However, the two separated while Jackson was pregnant with their second child in 2004. It was during that time when Federline, who made a living as a backup dancer, starting dating chart-topping pop sensation Britney Spears. Fleeting romance turned into a full-fledged love affair, and by July 2004 the chaotic couple announced their engagement.

Jackson later commented that the whole situation "wasn't like just breaking up a relationship. It was like breaking up a family." K-Fed and Spears tied the knot in September 2004. Two kids and one really bad reality TV show later, the couple filed for divorce by November 2006.