Mates are supposed to love, cherish, and protect each other. Alphas cannot live without their mates once they meet them, so they would have to be completely insane to reject their mate. However, some males set too high expectations for what their mate might look like. This is what happened to Serenity. Her mate wanted too much of her all at once, and he rejected her when she couldn't be what he wanted. But, she couldn't accept his rejection. That would send him to his grave, and she refused to kill him that way.