Rules of Stone by Alex Lidell

One elite fae warrior. Four superior officers. A bond they can’t remember—or resist.
Lera was once human. Now, with dark magic leaking into the mortal world, Lera and her four fae warriors must protect her home realm – even if that means going undercover to a human military academy. But when a sudden, terrible accident melds the males with their human disguise, everything changes. Now it’s up to Lera to make her mates remember themselves, their mission, and her, before the entire mortal world pays the price.
River, Shade, Tye, and Coal can’t overlook the gorgeous new cadet who’s just arrived at Great Falls Academy, but when the tantalizing Lera starts breaking rules and ignoring orders, the four senior officers intend to put her in her place. Lera will learn or she will quit—that is just how Great Falls works.