When Rowena and Amara were talking outside the warehouse where Amara and Chuck had their confrontation - Rowena had made a deal with her offscreen (of course it was all part of Chuck's plan) and Rowena was like, "So that's the deal - safe passage for me and my friend back in time before you end the world."

Which indicates that even if she had no intention whatsoever of keeping that deal, Amara had at least SAID that she would do it. :P