Cohen originally lied and took all the blame for Donnie. It was cohens confession that he didn't go to the Ukraine which led Republicans to claim that then the entire piss dossier was discredited. Once cohen seen that Trump was leaving him in prison to rot he started speaking out and telling the truth about piss mop Trump watching strippers pee in Nevada and many other lies and deceptions from convicted sexual predator trumpCohen betrayed the Don - or the Donny, in this case. So he was left to rot. The loyal felons who didn't rat the Donny out - i.e. Manafort - got pardons.
It depends on whether Donny was pissed at Rudy. Or whether Rudy had grovelled enough to get a favour tossed his way.