She is the wife of Mack Gerhardt, and she and her husband have two daughters, Lissy and Jenn. Mack and Tiffy have a very strained relationship; Mack's quick temper causes violent and abusive outburts, while Tiffy is a serial philanderer, most notably in an affair with the Unit's commander, Colonel Tom Ryan.
When first Kim, then Lissy, discover Tiffy's infidelity, her life begins to unravel: though she ended the affair before either of them learned of it, Mack eventually discovers a photograph of Tiffy with Colonel Ryan. After a tearful confession and threats of suicide, Mack has to be physically restrained from killing the Colonel.
Knowing that she has jeopardized her marriage, Tiffy files for divorce and takes a job as an exotic dancer to pay the bills, though she and Mack slowly resolve their differences.
Eventually, Tiffy and Mack salvage their marriage, but not before an accident in their garage (unrelated to their marital problems, forces Colonel Ryan to move Mack into the BEQ (Bachelor Enlisted Quarters), with orders that he is not to return to the Gerhardt home unless under escort by base personnel