In "One Flew Over Milwaukee", Duane the canary flies away which makes Shirley so sad that she doesn't even want to go to a party; she just mooches around looking dejected. Thankfully, there's a Happy Ending when Duane comes back.
In "Why Did the Fireman...", said fireman, who's been dating Laverne and is even on the verge of proposing to her, dies in a fire. Lenny and Squiggy enter and Squiggy doesn't say, "Hello!" like usual. They then shakily tell Laverne that Randy the fireman died, but she yells at them for joking and stays up all night waiting for him, refusing to believe it even when Shirley confirms the sad news. Frank then proves that Randy is indeed dead and Laverne breaks into tears.
In "New Year's Eve 1960", Laverne is crying because she got dumped and when Shirley says, "You might as well drown yourself in milk and Pepsi", she sticks her head in it! She cheers up soon after, but still.
In "Short on Time", Frank pulls out a Dear John letter and reveals that Edna (who previously disappeared soon after the show's move to California) left him for another man. Even though the person he told this to was a monkey — which he also cracked jokes with, this doesn't negate the heartbreak and sadness of the moment and in Frank's voice. Him sharing this with Laverne later on is also saddening but also a heartwarming moment between father and daughter.
