Which the least hypothecial end to be fair. Kou has shown no romantic feeling toward Nene and really want Nene and Amane to get back together.
For the moment as I said above, kou is a novice, a person who wants to help sad people, but she doesn't say she wants amane and nene to get back together, she wants to stop the sadness of both and the lie behind it.
And then how many times I've seen couples made for each other and that one of the two people finally doesn't feel the same thing anymore... There has already been a break caused by nene, we know that she won't hesitate for a second to come back with nene, but it's never been good the coupls that make a kind of break to come back together, it doesn't work so well (example in unrequited love between kaoru and reii).
There is still a lot of time and possible evolutions on the relationships of the 3 characters, we know that they will meet all 3 of them for photo sessions and other meetings a lot of things will happen.