The feelings he has for the girl might not actually be love, he could be in love with what he sees now, mistaking infatuation for love.

The girl loved him, but wasn’t ready to wait around while he got his shit together so she left. The chorus is him questioning how he can tell her, it’s the first time he’s experienced something like this so he’s not used to the feeling. The last part that speeds up and distorts is him realizing it all and reflecting on what he had. This occurs after the outro, which is set in the moment of the girl leaving and him talking with his friends. He’s trying to play it off to them like it doesn’t phase him but he writes “Hold up
I’m lying laying down in the bed uneasy but on the surface I’m fine”.