In 1917 and 1918 many new states appeared on territories of former Prussian, Austro-Hungarian, Russian and Ottoman empires; these include Ukrainian, Belarusian and Lithuanian independent republics.
I don’t blame Poland for fighting the Bolsheviks. Poland made a mistake in establishing a unitarian Polish state on territories of Ukrainian, Belarusian, Lithuanian ethnicities leaving little to Ukrainians, Belarusians, Lithuanians. Nationalistic motto of Poles were “od morza do morza” (Poland from Baltic sea to Black sea). It was a big mistake to build a unitarian Polish state that haunts Poland to this day in Ukraine, Belarus and Lithuania.
We may ally with Poland against expansionist Russian politics. In the back of people’s mind Poland is not trusted because of history.