The situations were different between Ireland and England.
The Normans invaded an Anglo Saxon nation. For centuries -- I think
two -- the upper class was Norman and spoke Norman French and
the lower classes remained Saxon. Those were hard times, to be
ruled by a king who didn't speak the language of his people and
imported strangers to rule you. The situation was awkwardly resolving
itself in the 1200's. The Normans didn't conquor the whole of Ireland.
They invaded it and established settlements, but couldn't launch an
attempt to displace the dominant culture and language. Many Norman
families assimilated into the Irish so that later when the English
did come to "conquor" her and irradicate the language and culture,
a number of indiginous Normans fought against them.