"The Big Bang Theory" eschewed the usual sitcom gimmicks — cliffhangers, last-minute objections, crazy impediments — and married off two of its characters in the 11th-season finale. The result was a terrific half-hour, managing to be funny, sweet and touching all at once.Much of that has to do with the unlikely, protracted and unorthodox courtship of Sheldon (Jim Parsons) — a man child always more preoccupied with science and his pop-culture pastimes than "coitus," as he insists on calling it — and Amy (Mayim Bialik), his equally awkward and brilliant companion. The idea of the two finding each other seemed improbable at first, along with Sheldon's ability to consider someone else's needs along with his own.The relationship, however, built over time, and actually resonates more deeply thanks to the spinoff CBS introduced this season, "Young Sheldon," depicting its protagonist as a child genius, surrounded by a family that doesn't know what to make of him.Seeing the "Young Sheldon" characters grown up and older — not only Laurie Metcalf as Sheldon's mom, but Jerry O'Connell as his brother — added a splendid wrinkle to the finale, as did Kathy Bates and the magician Teller as Amy's parents, the latter appropriately unable (mostly) to get a word in edgewise.The highlights didn't end there, with Mark Hamill gamely making a cameo as himself, drafted into officiating the ceremony; and Wil Wheaton back, lending dual "Star Wars" and "Star Trek" sizzle to this much-ballyhooed event.To their credit, producer Chuck Lorre and his creative brain trust weren't coy about the wedding. Rather, Sheldon and Amy got so caught up in a theoretical breakthrough that they had to be coaxed to the altar, before realizing there would be plenty of time for such pursuits later.The term "very special episode" is a cliche, a throwback to TV's old days. But Thursday's "Big Bang Theory" did indeed feel like an occasion, showcasing the cast's enviable chemistry — a group capable of eliciting laughs throughout the ensemble — and then augmenting that with all the high-profile guests.While there have been creative hiccups along the way, that dynamic underscores how the show has actually improved thanks to the ascendance of its female characters, compared to the early days, when it was the four guys and Penny (Kaley Cuoco). In that respect, the show has matured along with its characters as they enter new phases in their lives (marriage, parenthood), if, thankfully, not too much."Young Sheldon" has mirrored that template, closing the season with episodes that showcase Annie Potts, a fabulous addition as Sheldon's cranky but caring grandma."Big Bang" is heading into what most assume will be its final year, having reached the "Friends"-like stage where the decision resides with a cast that — having reaped millions from the program's success — is probably ready to move on.In TV terms, nobody could call such an ending premature. Yet the strength of the finale demonstrated that the show's continuing quality has perhaps been underappreciated in its later seasons, making the formula look deceptively simple. That's why whenever the finish comes, this multi-camera sitcom — likely one of the last true big-tent hits of that magnitude — will be rightly missed.