Roze understood that Rider and Waver were close. It was obvious from how Rider spoke of him that he considered Waver his partner. Although he didn't praise him in the way Waver might have liked, he praised him all the same.

But why did Waver always deny any affection for him? He'd be happier if he could relax about his relationship, wouldn't he?

It made perfect sense to Roze to encourage Waver a little. Not too much, just a little. They were practically dating already, so a nudge would only help them out. She had their best interests at heart.