Lifesong by Erin Lark
Everyone dies, and no one knows this better than Tucker--a shape-shifting wolf whose sole purpose is to sacrifice himself to heal the Earth.
Emma's insistence that her best friend is a talking wolf lands her in the psych ward. When she's released six years later, it's the wolf who takes her in. But the creature she bunks with in Maine isn't anything like the one she remembers from her childhood.
Tucker hasn't shared his bed in over a century. Falling in love the first time around ended with him having a broken heart inside the body of a wolf. He won't let it happen again--love be damned.
But when he tells Emma, a feisty blonde whose touch is just as fiery as her personality, about the pact he has with his not-so-immortal life, she does whatever she can to change his mind. Falling in love wasn't part of the plan, but now he's falling fast. And if that isn't bad enough, the mind-blowing sex and Emma becoming the pack's new alpha certainly add complications.
With the Earth crumbling beneath their feet, can Emma save the pack and the wolf she loves? Or will she make the ultimate sacrifice?