Lyric discussion by Serosaia 

My interpretation of this one is moreso about him trying to mend a broken down relationship, which was also once a strong friendship.

Build a lego house - to me would mean it as something that can be knocked down, but still can be rebuilt again.

Three words have two meanings - as a friend, as a lover. She is still there for him, and he will be there for her if she needed it

I'm out of touch, I'm out of love - He doesn't know how to show his love for her anymore. He finds his ways of showing his affection for her to appear unexistent. But he wants to show her, and he thinks he will 'love her better' learning from his mistakes.

I'm out of sight, I'm out of mind - She could have tried to distance herself from him, to try and get rid of those feelings, but he persists to carry on and promises he will make up for the mistakes.

Paint you by numbers - Trying to make her fully happy again and feel complete because of him.

Been here before - Self explanatory. He wants to give her his everything, in return for her trust to do the same.

Don't hold me down - He can't accept 'just' being friends with her. He needs more.

An error occured.