That girl seemed to only care about how Ten made her look as art of a "Price/Princess" duo. Of course Ten wouldn't want to be seen as an object, or worse, an accessory. Kinda ironic that she met an actual princess after that.
Sakuya is just another person who has mistaken the power to dominate for the feeling of love. She is pitiable, that way, even if she shouldn't get any until she at least tries to honestly make amends.
Also, it looks like Ten is not the only one with an unhinged ex...