Give it time. Russians typically don't take interference in their neighborhood too lightly.
Or we could just reunite
A few things about the difference between Belarus and Ukraine (at least in this situation)
1) historically, or at least the past two centuries, Belarus has been "closer" to Russia than Ukraine has. Even today the Church in Belarus is an exarchate I believe of the Russian Patriarchate. Belurisians have no foreseeable intentions of changing that status.
2) Ukrainian people have really received the short end of the stick compared to their Belarusian counterparts. A great example would be the Holomodor Genocide intentionally caused by the predominately Russian-run USSR. Or the various forced changes of property between the various sects under Communism. Many Ukrainian Catholic properties were seized by the Communists and given to the Orthodox. I don't think many were given back after the Wall fell.
3) Ukrainian Nationalism and the upcoming presidential election. The current Ukrainian government is run by nationalists. The nationalists are not all that popular in Ukraine because this mess going on the last five or so years was caused by the nationalists. So, the Ukrainian government petitioned the EP for autocephaly in a desparate bid to increase their popularity for the upcoming presidential election.
4) the continued decline of the Ecumenical Patriarchate. St John of Shanghai and San Francisco spoke about this in the 1930s and it exists on the internet. It is just as true today as it was in his day. This is another way for the EP to gain influence.
I think this whole mess is a travesty. I hate to sound overly pessimistic, but it would not be the first time that an entire Apostolic See left the Orthodox Church.