I Swear I'll Change

I'm not really sure about this but I think he's saying that he's seen this girls true face and he never knew that everything she was saying was just a lie. By saying, "Seeing everyone's true face Makes me wish they would keep their masks on Cause I don't wanna know, who you really are I thought you would have learned your lesson by now" he's saying that he liked her better when she was pretending to be someone else. When he says, "You and I will never be the same, You say you try, but you never change You can hide, and say you're not to blame I thought you have learned your lesson by now" he's saying that she can try and beg him to come back and say she'll change and become someone else but he knows that it's just another lie and they can never be with each other.