Wasn't it mainly the Zealots who were "upset that the Nazarene sect had not assisted in the resistance"?
The Zealots were upset (to put it mildly) with more than just the Nazarenes -- Johanan ben Zakkai and his group (Pharisees?) were also targeted, for example.
So as far as I know (and I admit I don't know much), early relations between Nazarenes and other Jewish groups weren't especially strained, with perhaps the exception of the Zealots.
The Pharisees were not of a single mind themselves regarding resistance to the Romans. The more accommodationist among the Pharisees were likewise targets of the Sicarii.
early relations between Nazarenes and other Jewish groups weren't especially strained
I'd agree if by "early" you mean from around 40-90 C.E.