On top of wasting refill slots, when bought, the new mythic books can not be offered to girls, AT ALL.
Complained to support. They don't understand the difference of affection and XP, say, it is supposed to be so and referring to the patch note about affection exceeding girl's capacity not being possible to offer.
XP has always been possible to preload a girl.
DO NOT PURCHASE MYSTIC BOOKS until they fix the bugs and teach their support what is the difference of affection and experience.