Malachite by Ashley Andersen

Malachite is the start of a dark academia romantasy series that gives you enemies-to-lovers, slow-burn, elemental powers, forced proximity, found family and the perfect amount of spice… 
 
Malachite. Opal. Agate.
Three stones, three powers, three magical units.
Choose your unit … and hope that it chooses you back.
 
Arianell Nocthare has been waiting her whole life to enter the prestigious Valmora Academy, where students prepare for war by honing their elemental magic in one of three units. But there are two problems facing Aria on the night of her initiation ceremony. Firstly, her family has been cast into disgrace after her brother was executed for allegedly killing four students in an attempt at dark magic. Secondly, so far Aria has been unable to summon any magic—and being magic-less in an academy where everyone wants to spill your blood is a dangerous game. How will she enter the unit of her choosing and survive without a scrap of power? 
 
Facing blatant scorn from every angle, especially from her brother’s best friend (the tall dark and lethally handsome, Sebastian) Aria is determined to clear her brother’s name and seek justice for his death.  Forging a tentative and fraught relationship with Seb, she begins to uncover some terrifying truths about the academy. And a revelation about Aria’s power throws her world into chaos…