He had tried, and of course by trying had been kicked aside, as usual. There was the Damon everyone thought they knew, and the real Damon. He didn't show himself often as he tended to get kicked in the teeth over it. Just like now. He had tried warning Elena, showing himself as he really was, made himself vulnerable. She'd turned on him. Big surprise.
Wallowing wasn't his style, at least that was what he told himself. So he headed to a bar on the outskirts where he wouldn't run into her or her lousy friends and got a drink. A kind of reset to be back to the Damon they all expected, the one that was useful. He might seem an asshole but no one else could make the choices he did to protect her. That would have to be enough. He hadn't protected Stefan, or Katherine, not that she needed protecting. In the end, it was his heart that had needed protecting. The doppelganger again picking his brother. Damon was getting sadly used to not being enough.