Tito died. As history teaches it is sometimes the case that when the top dog dies, lesser dogs compete, and are usually worse. Sidenote to Tito: Per the news of the day, he held the soviets at bay, which I think is impressive, although he was able to practice on the Nazis.

This from wiki:

Stalin took the matter personally and arranged several assassination attempts on Tito, none of which succeeded. In a correspondence between the two leaders, Tito openly wrote:

"Stop sending people to kill me. We've already captured five of them, one of them with a bomb and another with a rifle. [...] If you don't stop sending killers, I'll send one to Moscow, and I won't have to send a second."
— Josip Broz Tito[133]

Created in 1918 and arguably an artificial state, although not conclusively so, if it required a strongman with balls the size of Tito's to hold it together, it's understandable if the inner tensions released after his death blew the country apart.