Kate is obviously someone who can't cope with much of anything. It is clear that Kate is in fact the epitome of all that William wanted to escape while he was dating Kate. Second, Kate has got to get it into her thick head that as a public figure, people will take swipes at her and she refuses to learn and grow from this.
Kate can't cope rearing children.
Kate can't cope doing appearances that are not at all demanding.
Kate can't cope with the press writing about her.
Kate can't cope managing her own household.
Kate can't cope not being the center of focus even at events that are not supposed to be about her.
Kate can't cope with William being around.
Kate can't cope with William not being around.
Kate can't cope at Balmor@l or Sandringham.
Kate can't cope with doing engagements that are not local.
As for being peacemaker, Kate has done nothing but cause problems for herself, William, and the BRF ever since William let her into his bed. She's been freeloading off of a family and nation and she still can't cope. She is borderline nonfunctional.