Ebbie: Maybe "How could I forget?"
(Which is ambiguous as well; I like ambiguity in songs.)
Jeri: You might try changing the pronouns, and make it "he" instead of I, or the "you" to "her" etc. I'm not saying that's needed, but it might give an interesting angle. And Sirens in Grek mythology are not safe people to be around, they lure sailors to their death - I don't know if that idea is part of the image here, or if you want it to be.