Bite Harder by Jenika Snow

Forget the foreplay. For the truly committed, it’s all bite.

Willow has loved Devon and Case for as long as she can remember, but as lion shifters they will eventually find their mates. When she allows herself to be with her two lions after a drunken party, she fears she’s ruined a lifelong friendship and flees before morning.
Devon and Case have been inseparable since they could walk, but they can’t tell anyone that they are mates. The pride of shifters they belong to won’t accept a same-sex mating. But it’s not just their lives they have to worry about. They’ve also just realized they’ve become a triad with Willow—three shifters mated.

When a shocking revelation brings Willow’s world crashing down, she knows she can’t hide behind her fears any longer. Being with Case and Devon is the only thing that makes sense, and she doesn’t care if it ends up ruining their friendship.