She is the mess he made, he's looking at her hence the "And it's you" repeating lines. I think it's pretty obvious that Will cheated or came close to it judging by the "Should've held my ground" piece. All of the things he should have done (looked again), ie. thought about the decision more before he gave into it. In the end, nothing he can do will ever make up for it and the girl wisely took her heart and walked away.
She is the mess he made, he's looking at her hence the "And it's you" repeating lines. I think it's pretty obvious that Will cheated or came close to it judging by the "Should've held my ground" piece. All of the things he should have done (looked again), ie. thought about the decision more before he gave into it. In the end, nothing he can do will ever make up for it and the girl wisely took her heart and walked away.