Not going to fully blame him, but it's obvious his complaining to the refs is becoming a problem. I don't buy that it's a case that every single ref hates Milan or Romagnoli in particular, given that so many different ones have booked him. You can blame the ref as much for the harsh red (it should have been a 2nd yellow), but I saw clear issues with Romagnoli today.
When Suso was booked in the first 10 minutes for a clear tactical found from behind on Belotti, Romagnoli runs over to the ref and starts complaining. What exactly is he complaining about? It's the most clear cut yellow you will ever see, and every referee in every league will give that as a yellow. I'm all for the captain standing up and even pressuring the referee, but you can't be an idiot about it. Why would a ref take you seriously if you're complaining about the clearest yellow card? I'm starting to think it has to do with Romagnoli's constant complaining that he is receiving so many yellow cards, and I thought that was on display this game.
He needs to pick and choose when to complain. Starting to do that for the most obvious yellow card is not a good idea. He was asking for the red card by the end of the game.