In the following episode "My Brother 's Keeper '', Elena tells Damon he is the reason she and Stefan broke up and at the end of the episode Damon and Elena finally have sex. After that it turns out Elena is sired with Damon, first they think it is the reason why Elena loves Damon, but in episode "We 'll Always Have Bourbon Street '' they found out that it only affects how you act, not how you feel. The sire - bond can only be broken when Damon leaves Elena and tells her to stop caring about him according to a witch in New Orleans named Nandi. In the following episode Damon goes with Elena to her family 's lake house to help with Jeremy 's Hunter instincts. In the episode Elena tries to act like a couple with Damon, but he refuses to even kiss her out of his guilt about the sire bond and worry that he 's taking advantage of her. In the end of the episode Damon invokes the sire bond telling Elena to return to Mystic Falls while he trains Jeremy "O Come, All Ye Faithful ''. Elena kisses him goodbye.
when do damon and elena first sleep together
episode "My Brother 's Keeper ''