Goribu no Shoujo

Much like with the decline of humanity, the Girl is unable to understand the notion of love in a typical sense. She likes humans and does not have any distaste towards those that hold the notion dear, such as the group wishing to reinstill it as a core value of humanity, but she cannot understand what pleasure they obtain from it. She holds a more practical view that blind love can only lead to failure, instead requiring a method with a tangible benefit shown in how they support each other with a clear objective. Without the ability to see another's heart, she cannot comprehend the idea, so she instead imposes impossible tasks on those seeking her hand, hoping to instead have the suitor measure the love that she cannot. If they are able to retrieve something impossible to obtain that is more valuable than her and still exchange it to have her, she will see that as proof of their need for her and stay with that person for life.

(Source: TYPE-MOON Wikia)