Also...I believe she loves and appreciates her humanity. She may see full transcendence as tearing herself away from the connections both human and natural that she embraces. And yes, she knows first hand that utter and complete disconnect first in her sister Jean when she went DP and in herself with RS.
Yes her will power is indomitable...from outside forces but what if it's she herself who is the voice of temptation. How does she guard/stand against that?