I'm pretty sure that was Hermione.
I thought it was that ALL of the horcruxes were updated to 2.0.
From the description of HPMOR's horcrux spell, it won't work unless a witch/wizard is killed.
Edit: didn't see Nornagest's post.
The prophecy was only heard by Severus and Minerva.
Yours isn't the first I've seen guessing that ; it makes more sense than it being any OTHER Death Eater's arm.
Of course women would be smarter about sexual "utopias" than men. I mean no offense, biologically women have to be less impulsive about that sort of thing.
Hell, it wasn't even considered committed in the 80s. Although I suppose different regions may have changed faster, in the South in the late 80s/early 90s, "going out" was what we said for "going steady", while "dating" implied a more casual relationship. (And the actual term 'dating' was rarely used - I remember being asked, "you guys messin'?" after a couple dates with a boy.)
So yes, true.
Her maiden canon name is Black, not completely arbitrary.
My head canon is that Riddle seduced his own DADA professor when he was a 6th year, so when he investigated Baba Yaga's death that narrative rang true to him.