Did Harry get upset because Lupin resign from the Order of the Phoenix?

Yes, Harry was upset when Lupin resigned from the Order of the Phoenix. He felt betrayed and disappointed, as he admired Lupin and valued his support. Harry's emotions were compounded by the fact that Lupin's resignation was tied to the difficult situation surrounding the war and the challenges of parenthood, which made Harry feel even more isolated in his fight against Voldemort.