When Megan is mistaken for his queen and stolen by another seeking power over Rogue Stone, Gareth knows he must rescue her. Had he been at her side, she never would have been taken. Rescuing her forces his inner demon to acknowledge what he's been denying for far too long.
For far too long Megan waited for Gareth to notice her as something other than a healer. Being rescued by Gareth was one thing. Being subjected to the demands and strictures of his over-bearing protectiveness was another entirely. The only way to free herself this time might be to leave the realm of Hells Vein.
If she stays, Megan knows Gareth will never learn to accept her as a strong female. But, if she leaves, she'll rip her own heart out. Worse, by leaving, she may be damning them both to death.