Edit: What she's doing is reminding me of a friend I have. That friend has changed since, but she used to: flirt with boys. And then when they tell her they like her, she would say she doesn't like them back—but continously lead them on with hopeful thoughts, as she continues to flirt and be affectionate with them. And she does this because she liked the thought of many people being in love with her, it made her feel good. And I knew that because, she would constantly keep me updated on it, and even counted all the boys that has ever liked her. And I'll always label her as selfish and narcissistic, because she would hurt these poor boys only for the sake of feeling good about herself. She even told me that it's good to keep tabs on others and keep options available, even if she's dating. What is the word for a person like this?
But this is not like Risa at all. She's always said she likes those she's with, even if it usually doesn't last. She never leads anyone on - quite the opposite, she's rather frank about what she's like, and if she's over someone, that's it. Sure, she does enjoy being loved - surely everyone does - but I see no indication of her being interested in having many people keep on adoring her without giving anything in return like your friend; rather she's always been glad to return their feelings for as long as she was able to.
And that she has stopped this now is actually rather telling about how much she cares for Yuka, surprisingly even for herself.