- The ending of "I Don't Remember Mama". Especially with that very last line.
Grace: I remember that!
- The entire mini-arc of Fran getting pregnant and learning Maxwell doesn't want to have children, which makes it impossible for Fran to tell him. It gets worse when Fran suddenly suffers from abdominal pain and gets sent to the hospital. Fran discovers that her pregnancy test was incorrect and it was a false positive, meaning she was never pregnant to begin with. After Maxwell and Sylvia leave Fran's hospital room, she's getting her things together and then just starts crying realizing the baby she wanted so badly never existed in the first place, and all this emotional turmoil was for nothing. Thankfully, later on Fran gets pregnant for real, Maxwell is okay with it, and she delivers a healthy set of twins.
- Niles' heart attack in the season 4 finale. Coming off as quite the shock as Fran and Maxwell get a call and find out what's happened and even C.C. is shocked and actually shows concern for him as they were having one of their snark fests when he suddenly stopped and didn't say anything and she realized that he was in trouble and needed help.