We always heard stories of Alphas rejecting their mates, what if the Luna was the one not wanting the Alpha? What if no matter what you do, your mate won't say I love you. What if you try to make her happy, feel special, but she's still giving you the cold shoulder.
That's what Adriana did, she didn't want to give her heart away to her mate, scared that he'll break her. Giving him the cold shoulder was the only way she could think off to keep her heart in one piece.
But while doing that, she was killing herself in the process.