The only reason rinharu shippers ship rinharu is bc they wish they were haru. Why I hate makoharu: I understand how some people could prefer other ships, since I ship all types of things, but for me, Haru and Rin's dynamic is fun and sexy and powerful. I think Makoto love Haru more than a friend, but Haru didn't seem to reciprocate it that much?? No he doesn't. To me, Haru and Makoto have a close brotherly bond, whereas Haru and Rin have an intense rivalry that's fuelled by their friendship. Yes Makoto is still in Tokyo, but the director herself even states he doesn't see him as much as people seem to think he does.
So, if you want to ship rinharu, go right ahead.
To be honest, I do ship them. Tbh I don't think Haru will feel any sort of romantic love towards anyone besides water, and any feelings from Rin or Makoto will be unnoticed. Lots of wishful thinking. He's awkward and asocial, yet Makoto has always been there.
But I can only see their relationship up until that point.