Running with the Pack by Lola Glass

Never run from your mate. So there's a name for what I am. Ruby Wolf. And apparently, the rules don't really apply to us. For one, we come in pairs. The other half of mine is a douche named Ezra, and he's convinced that walking around naked is all it will take to talk me into choosing him. If we don't mate, I'll die. Period. End of story. But I won't betray Roman like that, so I'm dying slowly and painfully. Until he goes and signs up for the trials that can make him like me. The trials no one has survived in more than a hundred years. Things are pretty much a mess, but that's not new. I've survived worse. And if I don't, well, the last few months of happiness were worth everything and more. Contains mature themes.