"a source cloe to the show":
“It wasn’t 100-percent her decision.
It was a breakup. She wasn’t happy working on the show, and did that make her fun to work with? No. So everyone decided it would be in the best interests of the show, and for all concerned, if they parted ways. It just wasn’t a good fit.”
Rose also had troubles with the long work days and Vancouver in general (where they film)