After catching Dharma innocently hanging out with her old college tutor---and failed suitor---Charlie, an enraged Greg moves out. Then the misunderstanding turns into a crisis as they both get caught up in the planning of their mutual friends' impending wedding, compelling Greg to seriously reevaluate his own crazy marriage. But when he finally sees the light, it may be too late.
Fleeing from Kitty's talk on popular restoration of Victoria architecture, Dharma drags Greg into a neighboring high-school reunion for the class of '81, assuming the identities of no-shows Todd and Judy. She is non-plussed to discover that everyone present loathes ""Judy"" for the terrible things she did to them in high school, and decides the universe wants her to make amends by visiting each of Judy's former victims and apologizing. When this doesn't work out, she tracks down the actual Judy for a confrontation. Meanwhile, Larry offers Edward tips on how to revitalize the sexual side of his marriage, and encourages Abby to do the same for Kitty -- but their advice (""let the other make the first move"") leads to stalemate.
Dharma & Greg's love life suffers because neither of them can keep from helping other people with their love problems, including Greg's crazy, lovesick secretary Marlene. Their romantic getaway gets postpones so Dharma can set Marlene up with Jane's flaxy ex. Meanwhile, Abby comes up with a scheme to make money and feed Harry at the same time.
Dharma tries to reconnect with her old life by planning a wild road trip to Mexico with her friends. When Greg decides to go along for the ride, Dharma's friends are less than pleased. Meanwhile, Larry lands a job as a night security guard with Edward's company in order to get medical insurance for the baby.
In the fourth-season opener, Abby's plans for the new baby rattle Dharma, because Abby's admission that she and Larry made mistakes raising Dharma – like letting Timothy Leary babysit – threatens Dharma's memories of her childhood as idyllic. When Abby's pregnancy is threatened by complications, Dharma feels obscurely responsible, until a visit from the spirit of her dead friend George sets her straight. Meanwhile, Greg's advice helps Pete and Jane make a move to repair their crumbling marriage: they announce they are getting divorced.