1-He did not know about you and me.
Does this mean:
a-He did not know that we were having a romantic relationship
b-He did not know that something had happened to us
Could one say, for instance:
2-He knew that Harry, Jeff and Patrick were ill, but he did not know about you and me. (ie. he did not know that we were ill)
Navi, your first sentence would have been a more helpful title. We don't charge by the word.
and tells us nothing.
He knew that Harry, Jeff and Patrick were ill but he didn't know that we were. (There would probably be some emphasis on the word "we" when actually speaking this sentence.)