Although a smash in its first two seasons, Lois and Clark was, in some ways, reborn at the beginning of its third. Before Lois accepts Clark's marriage proposal, she reveals that she knows how super-unique he is. They eventually embark on a romantic relationship with all the trials and tribulations that come with it.
Almost midway through the season ("Ultra Woman") the two become engaged.
These episodes provided an engaging new direction for the series with Dean Cain and Teri Hatcher wonderfully playing off each other. It seemed as if the show would become the golden exception to the "Moonlighting" curse of having main characters get together.
However, this promising momentum came to a drastic halt when ABC televised what we were told was the wedding episode in February of 1996. The episode in question ("I Now Pronounce You...") became a bold-faced lie by the producers as it didn't end with a wedding between the title characters, but with Clark marrying a clone (yes, a clone) of Lois due to Lex Luthor's interference. To add insult to injury, the episode became the first of a Melrose Place-esque arc which would last an irksome 5 EPISODES, involving Lois getting amnesia, which prompts Luthor and then a unscrupulous psychiatrist to try to win her love.
This wasn't merely a case of a series going in a direction that most viewers disliked. This was a case of the show's loyal fans being deliberately lied to and toyed with for weeks on end. Not surprisingly, this arc led to many fans quitting their viewership of the show for good, despite a few watchable episodes at the third season's end and the characters REALLY getting married the following season, which, due to the drop in viewership, turned out to be its last.
If anything could be viewed as snatching defeat from the jaws of victory, it's the third season of Lois & Clark.