Basically, this song is about a boy that is deeply in love with a girl who apparently lost interest in him after they made love. I don't know why it's September gurl and December boy but I'm guessing that it refers to their personality. September is the month where school starts again and people start to work harder. So the September gurl is always busy and impersonal. December is the last month of the year and a vacation month, when we just sit down and start to think back "what the hell have I've been doing". It's a month full of deep thought. So the December boy is a time waister who is very personal.
Basically, this song is about a boy that is deeply in love with a girl who apparently lost interest in him after they made love. I don't know why it's September gurl and December boy but I'm guessing that it refers to their personality. September is the month where school starts again and people start to work harder. So the September gurl is always busy and impersonal. December is the last month of the year and a vacation month, when we just sit down and start to think back "what the hell have I've been doing". It's a month full of deep thought. So the December boy is a time waister who is very personal.