Vampire Diaries stars Nina Dobrev and Ian Somerhalder have officially thown in the towel on their relationship.A source confirms to In Touch that the pair, who dated for three years, have split.Shockingly, the news of their breakup comes only months after speculation that the two may have gotten secretly engaged."This may be the most epic night of my life. No explanation necessary. I'll leave it to the imagination," the beauty tweeted in February before attending Elton John's Oscar viewing party, causing many fans to speculate that they may have taken the plunge.But don't expect Nina to sit around and sulk about her heartbreak! Late last month, the bikini-clad starlet was seen frolicking on the beach with Julianne Hough—who called it quits with her boyfriend of two years, Ryan Seacrest, in March— and other pals during an all-girls vacation in Miami.After meeting on the set of Vampire Diaries in 2009, rumors started that Nina, 24, and Ian, 34, were an item. Although they began dating in 2010, they confirmed their relationship in the fall of 2011.