I wouldn't say Xi is the "only" one who can end it, but he certainly could. He also most certainly won't.

China recognized very early on that the US was trying to split China from Russia. If the US can balkanize Russia, China would be much easier to defeat. US neocons act like it is 1991 and there is no internet.

Anyone online can see through the pathetic attempt by the West to isolate Russia before moving to China, India and anyone else who won't toe the US empire line. The US is demonizing China nearly as much as Russia these days.

Simple geography says it would be more beneficial for China to be friends with Russia than the US. Then add raw materials.

China is smart to hold back on supporting Russia more than it does. If push comes to shove, I'd bet that China provides more support to Russia before it provides less.