Modern Divination by Isabel Agajanian

Aurelia Schwartz has spent twenty-three years maintaining the equilibrium between her carefully curated human life and the magical one that she endures in secret. With a devoted best friend and top marks at a prestigious university, she has everything one could possibly want neatly within her grasp.

Except, her gift of green magic has begun to fade, and if that wasn't enough to upset the balance of her life, a fateful run-in with another power-hungry witch with a penchant for stolen magic has threatened to bring it all to ruin.

Cast into an unexpected alliance with her dreadfully arrogant classmate, Aurelia goes into hiding among a peculiar family of witches, where she discovers that the secret to their safety requires breaking rules she has followed all her life:

Make no promises,

Tell no one what you are,

and

Never stay the night.