At Davos last year Manchin and Sinema high-fived each other then Sinema left the Democrats to go Independent and now Manchin is leaving the Senate.
Both moves help the Mitch McConnell led Republicans in the Senate.
Davos helped the RINOs IMHO.
Manchin is leaving the Senate under his own power to avoid the indignity of being fired. He "won" his last election with a plurality of the vote.