When Stefan taunts Damon about Andi, Damon makes it clear that he's just distracting himself from being in love with Elena. Stefan rubs Elena's love for him in Damon's face, adding that he's the one who has her and her respect -- something Damon will never have, so he's just fine with Damon loving his girl, because that means he'll protect her. The boys are attacking each other when Elena brings home Elijah, and informs them that the Fellowship of the Falls will be working with him to help with the Klaus killage while trying to keep Bonnie and Elena from dying. Damon flips out when Stefan agrees to go along and trust Elijah. And I know Damon is dangerously impetuous, but I can't help but think he's right in doubting that the surest way to save Elena is to sign on with Team Elijah. Elijah promises he will not bring any harm to the two Salvatores, provided he can have one thing from them in return -- an apology. Stefan apologizes for his part in killing Elijah, but makes clear that he only did it to protect Elena and that he will always protect Elena. Damon, on the other hand, tells them all to go to hell.
When Damon swans off to his room, Andi is lying in wait and throws herself at him, pleading with him to let someone care about him. Damon warns her off, but she won't stop being there for him. He swoops in on her and tells her she has to leave because he's in a dangerous frame of mind. When she refuses, he sinks his fangs into her throat, drinks and then tosses her on the floor. Andi sobs until Damon drops to his knees and compels or maybe just barks at her to leave before he kills her. She grabs her clothes and looks back at him one last time and then exits his room, with her clothes in hand. I love this scene like chocolate, first of all, because Damon is so conflicted and second of all because Damon is so conflicted. I mean it. I've kept my mouth shut for the last few episodes, but I was really wondering what happened to the screwed up Damon who Hamleted all over that girl he killed on the road, who was pretending to keep it together on the outside, but so screwed up on the inside, because Elena, darn her, was making him feel. Thank you, Show!