As much as I can’t stand the discussion about Ren’ai, the difference between Koi and Ai, and what the names put together stand for… I think I cracked Hino’s cheeky code despite the annoyance of this topic.
We like to use the terms to describe Yuuki’s love for either men but why not reverse it? I’m willing to bet Hino’s inside meta joke, her true intention of naming the girls those terms was not to indicate YUUKI’s romantic feelings for either men but THEIR romantic feelings for HER.
However! Only when you put both names together to be “ren’ai” is when it’s in context to YUUKI’S affections for both men. Since the term “ren’ai” is the complete package word usage for romantic love that is equal—requited. It’s a sickening twist to tell the readers, “haha, she loves them both equally—suck it.” Since it’s so much easier to hide behind such a term when you put both names of the girls together to encompass Yuuki’s feelings. It’s always the evasion to answer the question, “who she loves more?” Cause she doesn’t have to answer that question when you put the names together—she loves them equally, mutually.
Though, lemme break this down through the male love interests.
Zero IS in love with Yuuki, there is no familiar attachment for him—thus, Koi—this type of love is only used for romantic partners exclusively. Koi is used in words for unrequited love, too—which is how Zero’s love for Yuuki was since the beginning. Koi is a wanting, selfish love, of first, young love, of falling in love, it’s used for infatuation, of the start of being in love. Zero and Yuuki’s relationship is kind of selfish since they went against social norms to be together—at least because they were not meant to be since they were on opposite sides of societal social standings. However, despite all odds, Zero wanted to be with her.
While Kaname’s love for Yuuki is the term, Ai—it has the nuance of admiration, familiar love but also romantic interest. Ai isn’t a mutually exclusive term like Koi is when it comes to romantic love since it can be used to describe love between family and friends, too. It’s all mixed up for Kanaki since they’re family—descendants—they grew up first as siblings when Yuuki was born, but also promised fiancées. Ai is a giving type of love, it can develop deeper in context of romance. In Hino’s eyes, her ending narrative of Kaname made him out to be “always living for someone else” thus Hino’s use of a “giving” type of love. In general, it’s definitely got a double entendre that leads some credence to how brazen Hino used it for them.
When you see Ai in context of other phrases or terms, it doesn’t necessarily mean equally or mutually received in return, though.
It’s only when you put Koi and Ai—Ren’ai, that it means two people equally, mutually are in love. Hilarious, really.
Granted, this is just an inverse take of all the arguments I’ve seen and for all the years it’s been a topic of discussion. Take it as you will.