Watashi-tachi Fake Marriage?

Yata Hime has infiltrated the academy on a mission to root out its secrets.

Hoshino Hikari is another spy sent to the school, and in order to cover for her careless comments, Hime starts a fake relationship with her. But due to a charm spell that Hikari cast unintentionally, Hime has fallen in love with her.

As she tries to accomplish her mission as a spy and looks for a way to break the spell, the feelings between Hikari and Hime begin to change...

The academy's problem child, Yakumo Nene, secretly uses her "imaginary angels" in order to make some of the women there fall in love with each other. And today, she orders one of her angels (you) to bring Hikari and Hime closer together.

[From Steam]