It might surprise you, but breaking up with your best friend is actually more traumatic than calling it quits with your boy.
Professor Carol Smart, a sociologist at Manchester University, has found that the ethics of friendship - particularly between women - are so rife with politics that we feel incredible guilt about ending them, even when we know it's the "healthy" thing to do.
It's something these celebrities would be pretty familiar with - they've all split from their besties.
Heidi Montag and Lauren Conrad
The two stars' of The Hills friendship faltered due to the involvement of one Spencer Pratt. Heidi claims that Lauren was into Spencer, telling TV talk show host David Letterman, “She loved my boyfriend.” Apparently Lauren even told Heidi if she didn’t break up with him they wouldn’t be friends anymore.