Fergie married into a toxic family where convention and rules come before people and relationships. That she has been made an outcast is a reminder that nothing changes-- like Di, she has been made to suffer. Ok perhaps she hasnt always made wise moves, but lets talk about glass houses and stones! Whats all this anti Fergie about, she is just another woman sacrficed in the name of an institution that should have disappeared a long time ago, way past time---how about giving her some women support instead of falling foul of tabloid brainless tittle tattle, which is just as toxic!
Was she? Unlike Diana, she had very little in the way of Royal duties and was primarily a naval wife and mother. That is in itself a difficult life, involving frequent separations. And the paparazzi caught her with other men. Public evidence of infidelity causes a lot of marriages to fall apart - it's not a royal phenomena per se.