So right now things are like this:
Akira knows that she loves Rin, who loves Mayuki, who loves her, making a perfect triangle.
Rin just knows that Mayuki loves someone.
And Mayuki knows fuck all.
I think Detective Akira has the best chance at solving this mystery.
Jokes aside, the only pieces of the puzzle missing to complete the perfect triangle is for the triangle Akira knows about to work the other way too.
The easiest one is Rin, since she has some "ease" when it comes to falling for multiple people.
Then it's Mayuki, since she seems to have a really open mind when it comes to relationships, going by how easily she gave away her first kiss and was about to have sex too.
Now the problem is Akira. She'll probably open up after thinking it over and will actually be the one pushing for the triangular relationship just so that she can make Rin happy after understanding her feelings, but it's too early to say.
Next chapter is probably gonna dictate how the rest of the story goes, unless the author decides to stretch it out. I honestly don't see this story going past two volumes. And it shouldn't, really. The pacing is perfect so far. Here's hoping the author doesn't feck it up...
(I'm assuming it's gonna be a poly ending, since any other ending will be the end of the author's career, or even life.)