Is that like Captain America?
Do you think she will change her mind when she learns that Maya is an actual person?
A good way to explain Zahel without going into details is that he is a guy who finished his tragic version of the heroic cycle many years ago and now sits around with his regrets, accomplishments and grumpiness.
TRUTH!
She also feels a sense of personal obligation that I find quite interesting. Shallan's nature is to seek beauty both for its own sake and because she has chosen it as one of her life goals. To a person in her situation beauty is the time when pain, not just her own, decreases.