I have recently started a campaign at highest difficulty at Rome 2 Total war. It went pretty good, until suddenly half of my empire started a Civil war/sezession. I fought the betrayers and got my cities back, but not without huge losses, 2/3 of my armies wiped out, considering that approximately half of my army betrayed me. I started expanding again, but a few rounds later there was the next Secession. And that vicious circle repeated again and again until I lost the campaign. Honestly, I am pretty good usually and there was actually no chance of winning the campaign, half of your army and cities changing sides every 15 rounds or so.
Do you have any ideas? Maybe a DLC or some Political ideas? If every general is out of my house, do the armies stay loyal? I'd be pretty happy about help, I don't wanna play at an easier level but it's just annoying liker this.