Is it love, are they in love but just can't close the gap of understanding each other except expressing their love through intimacy using kissing and sex, am I right?
Well... yes and no. I've said most of this before in this thread, but I'll reiterate it instead of just posting quotes of myself to make the response more cohesive.
First, you have Rin. She doesn't understand herself very well, but she definitely knows she's not normal, and that bothers her ("I don't know what's wrong with me!" and other quotes from Raison d'être support this
). She also doesn't understand love in many different senses: she doesn't get the difference between a friend and a girlfriend, aside from physical intimacy, and I suspect that because she is aware that she is fundamentally not normal, she is unsure if she is capable of feeling love in the traditional sense even if she did understand it.
She definitely has some feelings for Hisao, though. As she says in the good ending, she is afraid of Hisao's kindness, and doesn't know how to feel when he treats her that way
. That can be interpreted as Rin experiencing a deeper feeling of love that she was previously completely unfamiliar with, and thus unable to cope with.
Hisao, on the other hand, is angry. In my first playthrough of Rin's route, I didn't really get how angry he was, because when I read through the scenes where Rin "rejects" Hisao's confession, and where she asks him to stay away from the atelier so she can paint, I understood why pretty thoroughly and forgave her for those actions immediately. Hisao doesn't understand and has a hard time forgiving. Those two rejections really
take a toll on him, and he is not over them by the end of the route. This is why he's hesitant to return Rin's confession when she says she loves him in Proof of Existence
But, like Rin, his feelings are undeniable. He reflects on how obsessed he is with Rin several times throughout the route. I think the best example is as he's comforting her in Raison d'être
, and he thinks about how the gravity of Planet Rin has pulled him dangerously close
There's still a gap between them at the end of Proof of Existence, but kissing and sex are certainly not the only ways they've been able to bridge that gap. A few notable examples where they seem to understand each other well are when Rin specifically asks to remain in Hisao's comforting embrace during Raison d'être, that being the kind of emotional closeness he desires most
; when Hisao helps Rin undress and get re-dressed after she gets caught in the rain
; Hisao's moment of pure white clarity at the beginning of Proof of Existence
; and most of the conversations between Hisao and Rin in Raison d'être and Proof of Existence. There was also a really beautiful point that someone else made somewhere (I think it may have been on Reddit instead of these forums) that Rin is fundamentally a creature of experiences, and Hisao is fundamentally a creature of words, but in the end of Proof of Existence, Rin decides to use words to express her love for Hisao with a verbal confession, whereas Hisao decides to respond with a kiss
. Thus, each of them puts their feelings in the form that is most easily understood by the other.
Now, unfortunately, there is bad news as well. Despite all this evidence of love and growing understanding between Hisao and Rin, there is a very strong case made through the text of the route that, essentially, true love is impossible. In both Raison d'être and The World Only You Can See (the neutral ending), Hisao tells Rin that it's impossible for him to truly understand her artwork, and by extension for anyone to truly understand anyone else, because the experience of life itself is just too subjective
. If you transfer that fundamental impossibility of human understanding to the realm of romance, you have to conclude that it's impossible for two people to truly love each other, as well.
Whether or not that is a depressing message really depends how you look at it. Personally, I try to take Rin's view on the matter:
Rin: "But isn't that terrible?"
Hisao: "I guess it is, in a way."
Rin: "I think it might make me sad after all."
Hisao: "Yeah. I know. I wish I could do something to help it."
Rin: "It can't be helped, I think. ...but... if you say that... It makes me feel a little better."
I interpret her last statement to mean that even if "true" love is impossible, momentary love - a connection between two people that makes them feel some sort of profound happiness or comfort, even if only temporarily - is still something to be treasured.