Lyric discussion by Valvakvlam 

Cover art for Sabrina lyrics by Einstürzende Neubauten

By the way: It says "a world of ruby all in vain" not "ruin". I would be interested to know what is meant by the stain on the morning sheets (menstruation?).

Not too far off. It likely refers to the loss of virginity or innocence. The stain is left on the sheets after her hymen is torn - following her first sexual encounter.