The Psychiatric Ward Theory:
all six friends are actually patients in a psychiatric hospital. Central Perk is the hospital cafeteria, their apartments are individual hospital wards, and their neat, happy endings (fame, family, wealth, marriage) are just coping mechanisms for their deepest psychological traumas
The entire show mostly recycles the exact same four or five indoor spaces (their apartments and the coffee shop). In this reading, Central Perk is the hospital cafeteria, the open field where they play football is the fenced-in institutional yard, and their codependent, insular behavior is the result of being cut off from the real world and terrified that someone will be discharged or taken away. Each character represents a specific, exaggerated personality disorder or psychological archetype
Perhaps instead of being six single adults living in New York, the friends are simply six patients in a psychiatric ward living out their dream lives together. Each of them has a trigger incident that lead to their admission: Monica’s damage from her mother, Ross’ trust and abandonment issues, Chandler's parents’ divorce and their bitter relationship, Joey’s unhealthy relationship with women, Phoebe’s troubling childhood, and Rachel’s realizations and running out on her wedding.
It certainly explains why they spent more of their time sat talking in a coffee house than actually at their jobs
Phoebe's Homeless Delusion:
Phoebe never escaped the streets. Instead, the entire 10-season series is just a meth-addled or cold-weather hallucination of a homeless Phoebe staring through the window of Central Perk, imagining an idealized life for herself and the strangers inside
Staring through the window of Central Perk, a destitute and traumatized Phoebe watches a group of well-off, attractive young people. To cope with her severe isolation and tragic past (such as her mother's suicide and growing up on the streets), she imagines herself inside their group, creating a safe, loving fantasy life. Theorists point to her odd, out-of-place skill sets—like mysteriously knowing multiple languages or showing flashes of hidden genius despite no formal education—as pieces of her real intelligence leaking into her daydream
One of the more depressing theories of the series is that none of it actually happened. A homeless Phoebe was just looking through the window of the coffee house and making up stories about the five people who sat there (who thought of her as “the lady who stares at us.”) All of their lives and relationships were just part of the personas that Phoebe created.
Afterward, she walks away, sees her reflection in a restaurant called “Ursula” before walking back to her park bench. It starts to rain, and she puts up a brightly colored umbrella. All the poor woman ever wanted was friends.
Rachel's Anxiety Dream:
the entire show takes place inside Rachel Green's head on the night before she leaves Barry at the altar in the pilot episode, playing out as a massive, subconscious anxiety dream about what her life would be like if she broke away from her wealthy upbringing
On a classic DVD box set cover art, Rachel is the only character with her eyes open while the other five characters sleep. Fans theorized that she was partially waking up from a massive panic-induced fantasy designed to let her escape a trapped, spoiled life of wealth and a loveless marriage
They’re All Just Day-Dreaming High Schoolers
Going again on the “it was all in someone’s head” theme, this idea suggests that the lives of the Friends that we see are just the daydreams of six high schoolers.
The reasoning for this is that the six of them, despite going through several ups and downs, all end up achieving their goals in adult life. They all have family, romance, and jobs
While there isn’t a lot of evidence to support this, especially as Phoebe didn’t attend high school, it does explain the wishful thinking of the friends and the way it all works out in the end.
Phoebe as a Secret Agent:
Phoebe Buffay's strange survival skills, fluency in multiple languages, and evasive past point to her being a covert operative—either a secret CIA or KGB agent
The Ross Custody Mystery:
Fans have long pointed out that Ross's son, Ben, completely vanishes from the show after Season 8. A dark fan theory claims Ross lost custody due to his escalating erratic behavior after the divorce and the birth of Emma
Ben is Ross’ son who his ex-wife Carol gives birth at the end of series one. Despite playing a big part in the early seasons of the show, he appears less and less as time passes. After the twelfth episode of season eight, The One Where Joey Dates Rachel, he is never seen again and mentioned rarely.
Ross certainly isn’t father of the year. When looking after Ben, he often leaves him in the care of his friends (who do things like leave him on the bus and teach him pranks.) Even when he sticks around, he does things like trying to stop Ben playing with his favourite Barbie! With that and his rage issues and his treatment of women, Carol could have won full custody.
That Monica is the result of Judy cheating on her husband
Judy’s treatment of her daughter throughout the series is downright terrible! More than once in the series she dismisses the idea of Monica ever having a family, which is especially wounding since a family is something Monica has always wanted.
While Judy could just be a terrible person, it’s been suggested that her mistreatment of her daughter actually comes from her own regrets.
That Monica is the result of Judy stepping out on her husband! Because of this, Judy resented Monica as she was a constant reminder of her betrayal. Her constant harassment is her taking out her anger towards her decisions on Monica.
There is a theory that Judy had an affair with Richard - which means Richard had both Mother and Daughter, which Judy of course knows but Monica doesn't
And the idea that Richard is the father of Monica - of course not - however it means that Judy had more than one affair, one Monica's father, two Richard, so potentially more
Did she have an affair with Dr Green for example
And if so, what if Dr Green is Monica's father - making Monica and Rachel half sisters all along - and maybe Judy isn't completely aware of this Mama Mia style, she just knows it isn't Jack
Emily Had Ross’ Baby
During season five, we see a lot less of Emily. Emily appeared in only fourteen episodes of the show and in season five, after the wedding episode, was seen only on a bed or with a suspicious pillow on her lap…
The reason for this is that actor Helen Baxendale was written out sooner than planned due to her real-life pregnancy. But it’s because of this that some fans think that Emily knew she was pregnant with Ross’ baby. She planned on telling him after the wedding but was too devastated by him saying Rachel. After trying to make her relationship with Ross work, she eventually decided not to tell him.
Phoebe And Joey Were Seeing Each Other
A question Friends fans ask every now and then: Why didn’t Phoebe and Joey get together? The rest of the gang seems to pair off and the two seem perfect for one another in many ways.
Well, in this theory put forward by Matt LeBlanc himself, the two had been together over the whole run!
It makes sense; the two of them often have casual relationships rather than committed ones. They’re never bothered by the other looking at them in a manner and they could easily have hidden it from the rest of the gang. It also adds another layer to Phoebe asking Joey to give her away at her wedding, as if she were closing the door on their relationship.
Emma And Ben Aren’t Ross’ Biological Children
Maybe Ross dyes his hair. maybe it’s something a lot more interesting than that! Some fans have suggested that the reason why Ross looks nothing like either of his children is that he isn’t really their father.
It’s thought (by some) that Carol and Susan tricked Ross into thinking he was Ben’s father, possible for his money or possibly to make keeping custody of a child easier, due to the lack of gay rights in the nineties.
As for Emma, maybe Rachel really believed that Ross was the father and was just wrong. Either that or she didn’t know who the real father was and thought it would be easier on Emma.