I think it's about a past relationship.
Sleepyhead is how he refers to his former loved one, someone who slipped away from him while he was still falling in love. All that has happened between them feels like a dream, as it felt to him like something real, but this other person walked away without even noticing his heart broke, how strong his emotional involvement had become.
And maybe this person tried to tell them this but he didn't hear them because he was so wrapped up in this feeling.
But perhaps they are still friends, or maybe they never became more than that, because he keeps repeating that "it's alright" and "[they're] all together", as if he believes that his emotions will fade or that he will realise that it was all illusion.
I think it's about a past relationship. Sleepyhead is how he refers to his former loved one, someone who slipped away from him while he was still falling in love. All that has happened between them feels like a dream, as it felt to him like something real, but this other person walked away without even noticing his heart broke, how strong his emotional involvement had become. And maybe this person tried to tell them this but he didn't hear them because he was so wrapped up in this feeling. But perhaps they are still friends, or maybe they never became more than that, because he keeps repeating that "it's alright" and "[they're] all together", as if he believes that his emotions will fade or that he will realise that it was all illusion.