Took long enough for someone besides me to realize this... and articulate it arguably better than I could.
Oh, when it comes to realize it I'm more or less certain that a lot of us had managed it already... it's the articulate it part where random has truly shined.
Btw, I don't know about y'all, but I find it quite amusing that Akira is the first one in the trio to understand all the sides of the love triangle they're in. Right now, she knows she loves Rin (duh), she knows Rin loves Mayuki, and she has just found that Mayuki loves her. Rin hasn't noticed that Akira loves her, and while she knows Mayuki has someone she loves she has no idea who that person is. And Mayuki, who has just confessed to Akira, doesn't know Akira loves Rin, and has absolutely no clue Rin secretly loves her.
... that last bit makes one wonder if Mayuki isn't a little bit daft, lol.