Hey Hey Hey, everyone! How are you all? Well after reading one review I realized that I forgot to explain what Austin was supposed to figure out. So here is what happened.
Ally wrote that chorus basically as a clue as to what she wanted to hear him say to her.
She knew that the most popular phrase would be I love you. Anyways as he thought more about which phrase would work, the I love you would keep coming to mind.
So then in the end he figured out that he did indeed love her.
So that's basically what it's about.