S5·E9 Hired Wife

Businessman Bill Connor comes with a startling proposition: he is single but pretending to be married in order to get a promotion, and needs someone to impersonate his non-existent wife at an executive party. Kate agrees with his stand against prejudice on the basis of marital status but then is attracted to a man who turns out to be a co-worker of Bill's. The whole farce turns out to be moot when Bill finds out the promotion was never available--the company was hiring from the outside--and quits, leaving Kate free to date Peter.