The first conclusive signs, we the audience notice that all is not well in Michael and Roth's friendship was when Michael and Roth gave [Kay's] that look at each, across the table when the Gold phone was being passed around but both Michael and Roth continued playing their cat and mouse games, each believing the other will never see the New Year

Michael's “Who had Frank Pentangeli killed?” set Roth off on his soliloquy
Roth was livid, Michael asking who gave the order for 'dead' Pentangeli because it had nothing to do with business same as Roth let someone putting a bullet through his loved and trusted, Moe Greene's eye go

However Roth's parting words to Michael, like their relationship is still good
Quote
That two million in a bag in you room. I'm going in to take a nap when I wake, if the money's on the table, I'll know I have a partner if it's not, I'll know I don't
Whilst Michael and Roth's friendship may have soured! their business relationship is still good?!

I am wondering whether Roth ever twigged that Michael had twigged it was Roth all along who set up the Tahoe shooting
If Roth did so at all when? What gave it away?

  • ”Pentangeli didn't run or hide after the shooting”
  • Michael didn't have Pentangeli killed
  • Pentangeli went to have the meeting with the Rosatos
  • Roth probably presumed Pentangeli was handing over the three 'promised' territories in the Bronx to the Rosatos in accordance with Roth's wishes!
  • Pentangeli and Rosatos meeting “signalled” to Roth that Michael “didn't suspect Frankie in the shooting after all--meaning that he must be suspecting someone else”
  • So whom did Roth think was that someone else? seemingly not Roth!

Roth and Ola didn't even suspect, there is no indication that they had figured they will never see the New Year
Otherwise Roth and Ola would not have been so slack considering how Michael's bodyguard, Bussetta was able to just walk into Ola's hotel room and killed him

If not for Roth's stroke, Bussetta would have probably murdered Roth in Roth's hotel room
If not for the Cuban Military Police, Bussetta would have been able to murder Roth, in the hospital

Roth came back to America to vote! not a concern that Roth could be murdered by Michael