"I can't believe we got engaged last night," Alex says to Whitney as he wraps his arms around her in their kitchen. Alex wonders what type of engagement ring to get her, but she quickly tells him she'd just prefer the cash equivalent. A traditional wedding is not their style, so they decide to head to City Hall that day to get married in front of a judge. "This is so exciting!" Whitney says. "From now on, if you want to leave me, you're gonna have to pay me."
Mark is freaking out in front of Neal as he comes to terms with his romantic feelings for Roxanne. "I can't stop thinking about her; it's really pissing me off." Mark asks Lily for her advice as she enters the apartment, but she's too shocked about the possibility of Mark having feelings for someone over 30 to give any feedback. Mark tells them he's infatuated with Roxanne, but he's also prepared to shake it off. "I'm Irish Catholic. I've repressed feelings all my life." Lily reassures Mark that it's best to repress; their group can't take any more stress or surprises. Suddenly Whitney and Alex barge in and happily tell the group that they're getting married.
"I am tired of getting free milk and I'd like to purchase this cow," Adam jokingly tells Alicia, the City Hall employee, as they walk up to the marriage license window. Whitney and Alex show Alicia two forms of ID; but they soon discover Whitney's driver's license has expired and she needs a current ID to obtain the marriage license. "Don't you have a database or something where you can look that stuff up online?" Alex asks Alicia. "Sir, this is City Hall... we don't have the Internet." Alicia replies. She recommends that they rush over to the DMV and have Whitney renew her license.
Whitney and Alex meet Vince, her father, inside a copy store that he's using for an office. "I can't believe it, my daughter's first marriage," Vince tells them as his boisterous personality takes over the conversation. He has Whitney's birth certificate, but he wants Alex to properly ask permission to marry his daughter before he hands it over. "May I have your daughter's hand in marriage?" Alex asks, to which Vince quickly replies, "For a price." An awkward beat hangs in the air until Vince admits he was kidding. "Congratulations, you are the proud owner of one Whitney Cummings. No returns." With the certificate in hand, Whitney hopes they can make it to City Hall before it closes, but Vince tells them it's too late; it closes at 4:30pm on Tuesdays. Disappointed in the day's outcome, Whitney and Alex decide to try again tomorrow.
Later that night, Mark tells Lily and Neal that he is completely over Roxanne. "Liking someone is supposed to make you happy; she's making me miserable." But when Neal tells Mark that Roxanne is on a date, his jealously rises back to the surface. Later, Roxanne arrives home with her date Nick in tow. Mark is immediately standoffish to Nick to the point where her date feels so uncomfortable that he leaves. "Did Mark see 'Drive' again?" Roxanne angrily asks Lily and Neal as they quickly exit the apartment. With the two of them alone, Mark tells Roxanne he's in love with her. Roxanne is shocked. "We're friends and I don't think we should be anything more than that." Mark hides his broken heart and quickly exits the apartment, leaving Roxanne alone, feeling awful for telling him the truth.
"It's impossible to make an honest woman out of you," Alex tells Whitney as they sit in their apartment after a failed day of trying to get married. He then surprises her with a diamond engagement ring. "I know you said you didn't want me to get you a ring, but I figured since we're getting married tomorrow, I might as well stop caring about what you want now." Whitney now understands why people like wedding rings, as she happily fits it on her finger. Alex carries Whitney to the bedroom as they kiss, but as he throws her onto the bed in the thralls of passion, Whitney bounces off the bed and slams onto the floor. She quickly pops up and finds her ring finger bent 90 degrees and broken. Off their frightened screams, they rush to the hospital.
At the emergency room, a doctor tells Whitney that they need to cut her engagement ring off ASAP or her finger will die. She reluctantly agrees but warns them to not cut off her middle finger; she needs it to communicate with strangers. Alex is worried that this emergency visit to the hospital is a bad omen and says maybe they shouldn't get married. "Your finger had an engagement ring on it for three minutes and it tried to kill itself." Whitney tries to calm him down and says, "The only thing this is a sign of is that we are going to get sooo much Vicodin."
The next day, Whitney and Alex arrive back at City Hall prepared with all of their documents and wait in line to speak with the clerk. Meanwhile, Mark, Lily, Neal and Roxanne wait for them in the hallway. "I would love a place to sit," Roxanne says. "Oh, is that something you could love!?" Mark bitterly throws back at Roxanne. Mark tells Roxanne that she just needs to see him with somebody else to realize what a great catch he is, so Mark suddenly grabs Lily and passionately kisses her on the lips. Roxanne calls Mark crazy, as Lily gleefully enjoys the signs of affection. "How is it that I'm the least sexually confused person in this group!?" Neal exclaims.
Later, Whitney and Alex are filling out the marriage certificate paperwork when they realize the clerk gave them divorce papers by mistake. Whitney starts to head inside to get the right paperwork when Alex stops her. "I love you," Alex tells Whitney, "but ever since you said yes to marrying me, nothing has gone right." He believes the fates are telling them not to get married, but to wait for another moment and keep what they have going for now. "I've been telling you that for three years, and the universe tells you for two days and you listen to IT?" Whitney asks. Even though they went through so much trouble in the past couple days, they decide to bail on the marriage and just keep what they have, two people madly in love with each other living happily unmarried.
Later, Whitney and Alex stand in a tattoo parlor gazing into each other eyes. "Do you really want to do this?" Alex asks Whitney. "I do," Whitney smiles back. As they kiss in agreement, we fade to them later that night in bed, each with a tattoo on their side ribcage with the phrase, "I do." Whitney lovingly watches Alex sleep when she tells him, "Don't fall in love with me." "Okay, I won't." Alex replies back as they both lean in for a loving embrace.
Season Finale! Whitney seeks her father's help when she runs into complications trying to obtain a marriage license with Alex.