In "Mork in Wonderland", Mork shrinks down and finds himself in an alternate universe, where Mindy has a counterpart named Mandy (but that's not the weirdest part). She ends up as a "surrogate Mindy" for Mork. In the end, while overthrowing the evil king, Mandy gets hit by an artillery shell, and dies in Mork's arms. Mork starts growing again and cries out in anguish "IT'S NOT FAIR!". Meanwhile, in our world, Mindy is tearfully packing up Mork's clothes, but then Mork grows to normal size and appears out of the tablecloth. They tearfully embrace.
Mork: It's selfish of me, and I know no one lives forever, but I hope I leave this world before you do, 'cause I couldn't stand to lose you twice.
In "Dr. Morkenstein", you'd THINK Mork crying over Robbie The Robot having a complete breakdown before dying would be pure Narm. But Robin Williams' acting was just so powerful.
Roddy McDowell (and the suit actor) mesh performances so well, you can almost see "Chuck" dying.
This one and Mork in Wonderland actually go over the same territory, but while Mandy's death is rather gratuitous. (The main ammo of the revolution is cream pies, and the artillery shell is friendly fire!). Robbie, meanwhile, is purely dealing with a friend who is growing old and senile.
In "Putting The Ork Back In Mork", Mork has started acting way too human, like a bland suburbanite. Mindy misses the old Mork, obviously. The montage (made of specially-filmed clips, not past episodes) of Mork & Mindy's life together set to "The Way We Were" is probably one of the most beautiful and heartbreaking montages ever put on television.
Mindy's nightmare in "A Mommy For Mindy", which is essentially a flashback to when her father told her that her mother had died. The nightmare ends with child-Mindy saying, "I Want My Mommy". Then we cut to real-life, where the adult Mindy is sobbing the same line as Mork tries to wake her up.
The final episodes. Mork, Mindy, and Mearth are targeted by Kalik, a psycho from Neptune, and as a result, Mork has to reveal his alien identity to the world. Mork & Mindy try to escape using Mork's time-traveling shoes, but Kalik follows them. At the end we see them falling though time together, wondering what will happen to them, but it doesn't matter as long as they're together. But that's not even the end. Because the real final episode is "The Mork Report", where they are somehow safe at home as Mork, trying to get a promotion from Orson, makes a report about his marriage to Mindy. Perhaps this is more of a tears of joy ending, since Mork & Mindy are shown to be very happy together in the end, and Mork gets the promotion. But still, it's sad to say goodbye to them, especially when you factor in the lostalgia.