Even though it would have meant removing a female character, Oppenheimer would have been vastly improved by removing most or all of the affair with the Communist sub plot. It added nothing to the story - other aspects already established that he had Communist affiliations and had loads of affairs - and all it did was add extra time, unnecessary and rather exploitative nudity, and a bizarre sex scene where he (mis-)quotes ancient texts in the middle of shagging.
But I guess Nolan had to include it to make up for the wife definitely not dying.
