Question about Roxanne Hart (SPOILERS)

Roxanne Hart played Camille Shutt, and I know the reason that the character left the show was that she felt "under-appreciated and disrespected" by the staff at Chicago Hope and decided to resign at the end of Season 2. But does anyone know the reason that the actress left the show? Was it her decision to leave or was she written out of the show, effectively being let go?

The reason I ask is that I found it a little bizarre that all through Season 1 they had this big story arc revolving around her and Aaron separating, planning to divorce and then reconciling. She told him she loved him more than any other man and couldn't live without him. Then by the first episode of second season, Aaron decides he wants to leave her, within a few episodes they've gone through with the divorce and both seem generally ok with it, and by the end of second season she resigns and the actress leaves the show. Was it always intended to be like this or was the original intention for Aaron and Camille to be together but the actress wasn't working out so the writers slowly wrote her out of the show?

I'm just wondering if anyone heard anything, because it seems weird that they would do this big romantic build-up to her and Aaron reuniting and being meant to be together, only to have it not work out and have her leave soon after.