Dean had gotten married to Lindsay, he had a great relationship even after the break up of you two. Luke started noticing that Dean still had his eyes on you, from when he was saying your name while he was drunk, to comforting you when having a bad day, then losing focus while at the arcade since you were across the street. Luke decided it was enough and notified you to confront him, so you gave in soon enough. You met him at the park.