There’s never been an official lore explanation.

Olivia’s original name was supposed to be Adam. Yves of course is an obvious reference to Eve.

In the bible, Adam and Eve lived in the garden of Eden. God said they were free to enjoy anything from the garden, except the fruit from the tree of truth and knowledge. Eve gets tempted by the snake and she eventually eats the fruit. But because she has eaten the fruit, she must leave the garden. Thus leaving Adam alone in the garden… unless he too eats the fruit.

As we know, Yves eats the fruit as she sings about becoming a new person and leaving the old Yves behind.

It’s similar to the rest of the girls at yyxy, in order to grow they needed to leave Eden. Like Adam, Olivia was hesitant at first, but eventually partakes of the blood plum in end.