Daniel tried to ally with the Hungarians and Lithuanians and the West, and where did it go? Nowhere. Well, actually, somewhere:Poland and Lithuania brought his dynasty and kingdom to and end and divided it amongst themselves.
But that did not destroy Orthodoxy - on the contrary, some Lithuanian high princes (Lubartas, son of Gyadiminas) converted to Orthodoxy and made the "old Ukrainian" the language of their court and courts of law. Later, things became tougher because of the Polish-Lithuanian Unia, Counter-Reformation, Jesuits, etc. Still, Orthodoxy was alive, the cities like Ostroh, L'viv, Kyiv were centers of Orthodox learning ("Brotherhood Schools"), peasants were literate, Cossacks defended the people well (not always, but they did what they could), so we (the "Rusy," "Rus'," "Rusyny," whatever) - lived. Our identity remained alive. On the other hand, in the Great Principality of Muscovy things weren't at all that good. The entire life of the people ()the Moskovity or Moskovlyane) was "Tatarized." There were virtually no schools, no learning. Peasants were bonded serfs. Boyars were savages, even in the Duma (Moscow Great Prince's Privy Council) some members did not know how to read or write. We ("Rusy," "Rus', "Rusyny," "Rusychy") actually brought culture and learning to them (Moskovites) in the 17th and 18th centuries. In gratitude for this, they enslaved us and stole our name.