Elena wanted to show that she has the man Mia couldn't and also to make other people know she is with the one who bought the imperial seal.
So she started a conversation with Damon saying
"Hot shot, look how you made them filled with jealousy"
The conversation they were having made him laugh, turning his face away from Elena his eyes went straight ahead to see Mia and Lucas equally laughing together. Seeing Mia in this beautiful amazing dress, he became jealous and wished in his mind that she was with him.
And all the words Elena had been voicing out ever since he started staring at Mia was all a waste. He wasn't listening.
After asking a question hoping for a reply from Damon, Elena then noticed that his mind wasn't here so she nudged at him and asked
"Are you with me?"
"Oh, yeah
