8. Zac Efron and Vanessa Hudgens
Few people in life end up with their high school sweethearts, so it's not really a surprise that the High School Musical co-stars have parted ways. There was no drama, no cheating, no scandal - how very un-Hollywood of them. According to E!, friends of the couple said, "They were together for so long. It just ran its course." Of course, if Vanessa wanted Zac to "put a ring on it", she was probably going to have to wait quite a while. In a 2009 interview with GQ, Zac said he had no plans to make it legal with anybody, telling the magazine, "I'm definitely not getting married. In this business, you're either getting married or they want you to be pregnant. I'm not getting married until I'm 40. If ever. The thought never crossed my mind." More realistically, the couple's busy schedules most likely fueled the end of the relationship.