Charlie runs into a former girlfriend who's son looks a lot like he does.
After borrowing money from Alan, Charlie loses his temper when Alan demands repayment and kicks Alan out of the house.
Charlie decides to take a break from womanizing and experiments in the kitchen while Alan tries to juggle going out with two women.
Charlie works his magic on Alan's receptionist as Alan anticipates the worst.
The guys bump into Jake's former teacher who became a stripper after a fling with Charlie. Charlie tries to help her out by giving her a room and a job, but things spiral out of control.
When Herb gets kicked out of the house, Alan tries to resume his place with Judith.
Charlie tries to introduce Herb to his lifestyle while Alan works to free himself from Judith.
Charlie's latest girl is tired of always staying with him, and asks him to stay with her once and a while. Alan tries to enforce his parental authority.
When Charlie's intimidating new neighbor comes looking for Jake and his teenage daughter, Charlie tries to cover for him.
When Jake's grandmother offers to finance his higher education, Alan ponders the need to keep working.
Charlie re-examines his lifestyle when an old friend who led a similar life passes away.
Jake challenges Charlie in a play for the attention of an attractive waitress. Meanwhile, Alan and Melissa confront the attraction between them.
Judith is pregnant and Alan, after their one-night stand, worries that he might be the father. Meanwhile, Jake is in a bad mood and Charlie is convinced he knows why.
Alan begins to believe that his family doesn't appreciate him, leading him to move in with Melissa and her mother.
Charlie agrees to attend couples counseling with Chelsea.
Charlie panics when he has to remove a half-naked woman from his bedroom before Chelsea arrives.
Charlie admits to Chelsea that he is in love with her, but the response he receives is not what he had expected.
When Chelsea gets sick and Charlie has to take car of her, he must fight the urge to leave.
After Chelsea discovers a nude picture of another woman on Charlie's cell phone, he blows off steam by going out for a night of drinking with Alan, Herb and his neighbor.
Evelyn and Chelsea meet for the first time, and Charlie wants to make sure they never become friends.
Chelsea is asked by Alan to arrange a blind date between he and her new friend, unaware that her new friend is Rose.
Charlie mourns the loss of his bachelor pad as he reluctantly allows Chelsea to move in. Meanwhile, Alan discovers there is no longer much space left in the house for him.
As Alan and Chelsea bond, Charlie uses the free time to do the things that he likes to do on his own.
After hearing Mia is back in town, Charlie begins questioning his relationship with Chelsea. Meanwhile, Charlie, Alan and Herb rush Judith to the hospital when she goes into labor.