Suzanne Somers vastly overstated her own importance when it came to THREE'S COMPANY. I heard one biographer say it this way -- Ritter was the star, DeWitt was the actress, and Somers was the celebrity.
Not entirely wrong, but I'm unsure if I entirely agree.
Somers wanted $150,000 per episode in 1980, and she quoted the salaries that Alan Alda and Carroll O'Connor were getting on their respective shows. I believe she edged for either 10% of the series' revenue or ownership in the show, too. The producers were baffled, and understandably so. What Somers and her agent-hubby Alan Hamel didn't seem to "get" though was M*A*S*H and ALL IN THE FAMILY had been on for years, raking in awards and high ratings. THREE'S COMPANY was still in its infancy, and Somers wasn't really in any position to demand so much.
Had Somers gotten Ritter and DeWitt to stand with her... Well, ABC might've sweetened the deal, but they wouldn't have given a raise drastic enough to please Somers.
ABC had also dealt with Somers' agents and PR people before, as they handled Farrah Fawcett and her 1977 exit from CHARLIE'S ANGELS. The brass at ABC were apparently determined not to get swindled with Somers like they had been with Fawcett.
If one needed to be named, John Ritter was the star of THREE'S COMPANY. DeWitt and Somers had a "favored nations" clause in their contracts that said they got equal pay, but Ritter's contract held a clause that stated he got more per episode than either of the girls along with his star billing.
ABC simply wouldn't raise Somers' salary to a level she saw fit, but they kept her under their thumb. ABC threatened to sue if Somers' new sitcom deal at CBS presented any similarities whatsoever to "Chrissy Snow" -- a decision that pushed CBS to buy out Somers' contract and shelve her pilot for THE SUZANNE SOMERS SHOW.
ABC took a stab at Somers' popularity. They dwindled her part down for the remainder of the 1980-81 season, and she only appeared sporadically in the "tag" of episodes. Still, the producers deemed the "Suzanne Somers" important enough to the show not to change the opening credits for the season -- which, another reason could've been their decision not to dish out any more money than they were already having to.
It was all a mess, and it took years for the trio of Somers, Ritter, and DeWitt to work everything out.