Of course it's about sex! AND, she doesn't want to admit it.. for all you young people out there. An 'afterglow' is the feeling you get just after having sex. I learned that word when I was in junior high. :razz:
She says "and I'm walking free, the wind at my back, bathed in afterglow". She just came home from a night out and she is walking home in the morning (the "orange sky"), and she is still feeling the effects of her night with a lover. And, she was there in the dark room seeing blood.. hmm, maybe just lost her virginity??
hahaha.... well, ok that is the literal meaning. The figurative meaning is a period of time where she is in a relationship. The time frame goes from winter (days getting colder) to spring or summer (days getting longer). Her afterglow in the figurative sense is the way "her lover" makes her feel all the time. Like she is in a constant state of afterglow (from having sex).
Sooo... it IS about sex, yet it isn't.
