I don't know if "fail" (https://www.datalounge.com/thread/30673988-why-did-mary-tyler-moore-fail-after-her-sitcom-ended) is the right choice of words given that she was nominated (https://en.wikipedia.org/wiki/Mary_Tyler_Moore_filmography_and_awards) for a Best Actress Oscar (https://en.wikipedia.org/wiki/Best_Actress_in_a_Leading_Role) for Ordinary People in 1980. But all of her subsequent television shows that had her in a leading role barely lasted a season:

Mary (https://en.wikipedia.org/wiki/Mary_(1978_TV_series)) (1978) - This is probably most notable now for featuring a then unknown David Letterman and Michael Keaton.

The Mary Tyler Moore Hour (https://en.wikipedia.org/wiki/The_Mary_Tyler_Moore_Hour) - Michael Keaton was also on this show.

Mary (https://en.wikipedia.org/wiki/Mary_(1985_TV_series)) (1985) - John Astin (AKA Gomez Addams) and a pre-Married...with Children Katey Sagel were among MTM's co-stars.

Annie McGuire (https://en.wikipedia.org/wiki/Annie_McGuire_(TV_series))

New York News (https://en.wikipedia.org/wiki/New_York_News)


None of these shows lasted longer than 13 episodes let alone a single season. And New York News appeared to be the proverbial straw that broke the camel's back (https://tvtropes.org/pmwiki/pmwiki.php/Main/StarDerailingRole).

I was a huge fan of Laura Petrie, being so good looking yet meek and vulnerable....was a very appealing package.

And I watched the MTM show religiously when it was in first runs.

Something just changed about the dynamics. The political injection of stereotypes didn't weather well, and it made the lead actor somewhat of a poster girl for a revolution that I didn't find entertaining.

Once the cache that Laura Petrie had accumulated had become depleted....my interest waned, and I stopped following her..