She tries to put on a brave face about her marriage, but she is in distress over her seeming inability to conceive a child. During the initial stages of her husband's sexual studies, she fears her husband's lack of intimacy is a result of her perceived condition and becomes increasingly desperate to solve the problem.
She is also confounded by her husband's clinical interest in sex, but apparent lack of desire to share his passion in their marriage. Libby believes that she can only be the perfect wife if she can provide a family for William. At the time, she is ignorant to the fact that William Masters has a low sperm count and believes she is infertile.
In the first season, Libby wants a child, but Bill cannot tell her that his sperm count will make it impossible to conceive a child. She eventually becomes pregnant through fertility treatments, but suffers from a miscarriage. Despite Bill not wanting to try again, Libby becomes pregnant again and gives birth at the end of the season.
Libby is distressed as Bill cannot seem to maintain a job,, especially as there is a newborn to have food on the table for. She hires a nanny for baby Johnny, an African American girl named Coral. Libby is concerned by Coral's boyfriend Robert. After witnessing a hate crime, Libby works with Robert at the CORE headquarters in Bill's new office building. They later have sex and Libby admits she's known her husband has been having an affair for years.
Libby bonds with her next door neighbor, Joy. After Joy has an aneurysm, her husband Paul is left to take care of her, even though she can barely speak or move. Joy later dies. Libby and Paul begin connecting, and Paul admits he has feelings for her. After their relationship becomes intimate, Paul proposes to Libby. Libby later realizes that the relationship will never work because she wants to keep her family in tact, so she calls off the engagement.
Bill and Virginia are arrested for prostitution, since Bill paid Nora. Libby talks with Bill and Bill finally confesses that he's been having an affair for ten years. Libby says she knows about this and the two fight, with Libby leaving Bill in jail.
Libby and Bill plan on having a divorce, after Bill revealed he has been having an affair at the end of the previous season. However, their relationship softens throughout the season. Because of their legal issues, Bill's lawyer, Bram Keller, tries to get Libby to not pursue the divorce until after the trial ends. Libby and Keller go on to develop a close, intimate relationship.
Keller invites Libby to go to a nudist colony, who are some of his newest clients. To prove she is not a prude, she goes to the colony and enjoys her time there.
Libby begins looking for a job, and starts by working as a secretary for Herb Spleeb, a lawyer located in Bill and Virginia's building. After an incident at a local diner, Libby wants to practice law. Libby goes to Woodstock after being stuck in a traffic jam, and while there, finds a connection and decides she will study law at Berkely in California and take the children. Before leaving, her and Keller have a peaceful breakup, and after getting into the car, Libby assures the children that "the future is happy and bright".
Libby has appeared in every episode to date, with the exception of In To Me You See.