They had a plan—stay together, search for Mage journals for something good and important to do.
She had other plans.
When Zelara abandons the party in the night, she leaves a note for Taeryn telling her where she's gone.
Lensilia, on her own, with the help of a Blue Mage.
When Warren is sent after her via magic, to give her time, the party remains split. Zelara and Warren spend time in Lensilia; the remainder of them take the long way, traveling by horse from Shadowfel with the addition of an Elf needing an escort back to her home.
Being determined to speak with Hale's mother and face the truth sends Zelara and everyone she cares for on a path that can't be turned back from.