I think this is about a relationship where they're not telling each other enough, there's too many games and it's driving him crazy. The 'too young' he describes her as is not actually implying to her age, it's calling her immature and saying how she doesn't understand how this is upsetting him. The 'no-one thinks what I'm doing is the right way forward, You'll see it's not just a dream now' is about how his friends are telling him he might lose what he has if he confesses everything and they're telling him that it's all in his head but he's going to prove to them 'its not just a dream' and show them that something is wrong when he speaks to her. The 'you think you know, you don't know' is just him saying how much she thinks she knows what's going on but she really has no idea. The costume party bit is him having finally spoken to her and she said something honest that caused him to end it therefore this big 'costume party' that is their relationship being over, before he even gets a chance to fix it.
I think this is about a relationship where they're not telling each other enough, there's too many games and it's driving him crazy. The 'too young' he describes her as is not actually implying to her age, it's calling her immature and saying how she doesn't understand how this is upsetting him. The 'no-one thinks what I'm doing is the right way forward, You'll see it's not just a dream now' is about how his friends are telling him he might lose what he has if he confesses everything and they're telling him that it's all in his head but he's going to prove to them 'its not just a dream' and show them that something is wrong when he speaks to her. The 'you think you know, you don't know' is just him saying how much she thinks she knows what's going on but she really has no idea. The costume party bit is him having finally spoken to her and she said something honest that caused him to end it therefore this big 'costume party' that is their relationship being over, before he even gets a chance to fix it.