When the IRS decides to audit Oscar and his ex-wife, Gaby, Felix offers to mediate between the contentious exes and suddenly realizes that he might be the reason Oscar was audited in the first place.

Oscar reconnects with many significant people from his father's life when he agrees to carry out Walter's last request to spread his ashes behind the candy factory he once owned.

When Oscar and Felix attend the wedding of an old college friend, Oscar aims to reconnect with an old flame while Felix is determined to show his ex-wife that he’s a changed man.

Felix forces Oscar and Emily to go on a date to get to know each other better in the hope that they’ll become friends. Also, Teddy agrees to help Dani with her first contract negotiation.

Oscar is forced to choose between his romantic plans with Charlotte and helping to save Felix’s relationship as Emily decides to extend her stay in London and Felix starts to fall apart.

Oscar faces a personal dilemma when he dates a young nanny, Allyson, who works for his neighbor, Charlotte. Also, Emily forces Felix to participate in an activity she's interested in, for a change.

Things get out of hand when Felix begins to meddle in his friends' personal lives and hires a counselor to help resolve their issues. Among the problems: Teddy's wife Diane believes that he is cheating on her with Dani after he stays out all night and Dani's moving in with Emily has created friction over the way the apartment is decorated.

Felix takes the first step in moving on from Emily by picking up a bartender named Natasha (Busy Philipps) and bringing her home for the night. It later backfires when Felix doesn't know how to have a one-night stand; Natasha starts to get attached and won't leave. Meanwhile, Oscar takes his relationship with Charlotte to the next level by asking her to leave her toothbrush at his apartment, after which they get into a conversation about their relationship and say "I love you" to each other.

With the help of Murph, Oscar decides to throw a big party when Felix finally agrees to spend the weekend away. Also, Felix and Emily have their first sleepover.

Oscar attempts to impress Charlotte by purchasing a table for a fundraiser to benefit The New York Philharmonic. At the event, Felix reminds Oscar about the importance of being honest and Teddy introduces his wife, Diane, to Dani for the first time.

Oscar and Felix run a heated campaign for president of their building’s tenants’ association, but Oscar doesn’t fully realize everything the position entails.

Felix’s hypochondria kicks into overdrive when Oscar starts dating the most important person in Felix’s life – his doctor.

After Oscar and Felix become obsessed with eavesdropping on their bickering neighbors, they try to subtly intervene and help them save their marriage. Meanwhile, Emily and Dani's friendship is tested when they train together to race to the top of the Empire State Building.

Oscar and Charlotte hit a speed bump when they hesitate to take their relationship to the next level. Also, Felix attempts to overcome his fear of dogs with Teddy's help when Emily regains custody of Biscuit.

Oscar reluctantly agrees with his agent that it’s time to shake things up on his radio show and allows Dani to have a bigger role after a rival host, Rich Eisen, taunts him. Also, Felix is eager to meet Emily’s mother, Judy (Joanna Cassidy), but things don’t go as well as he hoped.

Felix attempts to reverse Emily's birthday curse and plans a nice dinner to celebrate with friends. Also, Oscar and Charlotte face another obstacle in their relationship when Oscar meets Charlotte's son, Evan (Caleb Brown).

In an attempt to surprise Emily, Felix gets his learner’s permit and enlists his friends to help him learn how to drive. Also, Oscar is annoyed that Felix doesn’t ask him for help,

After Murph persuades Oscar to try online dating, Oscar finds himself on a blind date with Felix’s ex-wife, Ashley.

Felix goes into a frenzy when the responsibility of hosting the Unger family Christmas falls onto his plate after his perfectionist mother bows out. Meanwhile, Oscar tries to convince his roomie's mom to give her son a break.

After a heated argument, Oscar and Felix decide it might be best to change their living arrangements and find new roommates.

After their marriages fail, Oscar and his former college roommate, Felix, decide to live together.

When Oscar realizes he forgot Felix's birthday, he plans an impromptu surprise party.

Dani wishes she had a boyfriend for her high-school reunion so Oscar, Felix and Ted work on finding her a man.

When Oscar and Felix make a trip to Ashley's to retrieve Felix's special pillow, a secret that he has kept from Oscar is revealed.

Oscar becomes weirdly obsessed with living up to Murph’s reputation when he finds out that the girl he is seeing used to date the handsome ex-baseball player.