Ross

Rachel is perhaps most famous for her turbulent relationship with Monica's brother Ross Geller. Ross had apparently harboured a crush for Rachel since ninth grade. When Rachel moved to the city, Ross tried to re-kindle his affection, and after a rocky start the two finally got together in "The One With the Prom Video". After an argument over Rachel's friendship with a male co-worker, Rachel announced that they were taking "a break." Ross, thinking that Rachel was ending the relationship, got so drunk that he slept with "the hot girl from the copy place," Chloe. When Rachel found out, she broke up with Ross in a famous scene that involved Ross and Rachel arguing in Monica's living room while the other four friends were trapped in Monica's bedroom. From then on, the two shared an almost-on again-almost-off again relationship. When Phoebe fixes Ross up with her "bald friend Bonnie," Rachel is clearly jealous when she sees that Bonnie is no longer bald, with beautiful flowing hair. In the episode at the beach, where Phoebe learns the true identity of her birth mother, Rachel convinces Bonnie to shave her head again. When Ross asks her why she did it, Rachel admits that it's because she still has feelings for him. While Ross is next door breaking up with Bonnie, Rachel pens a rather long letter to Ross (18 pages, front and back!) asking him to take responsibility for their first break-up. However, Ross falls asleep while reading the letter, and later bluffs that he agrees with what the letter has to say. Only later, when the pair are in bed, and Rachel is saying she's glad she didn't accept her mother's advice "once a cheater, always a cheater" that Ross finally understands the content of her letter. A very loud "WE WERE ON A BREAK!" is heard being shouted by Ross from the bedroom.

Rachel's jealousy of Ross's girlfriends continues when Ross meets Emily, and Rachel deliberates for some time before deciding not to go to London for the wedding, citing that "it's Ross" and that it would be too painful. However, she later changes her mind and against the advice of Phoebe she flies to London just in time to see Ross before the ceremony. This results in Ross saying Rachel's name instead of Emily's at his disastrous wedding ceremony in London. When Ross's new bride does not appear at the airport for their honeymoon, Ross instead invites Rachel to accompany him to Greece. However, Emily making a show at the last minute sees Rachel sitting on the plane. When Ross sees Emily running away, he chases her. Aboandoning Rachel on the plane to Greece. When Rachel returns from Greece, she is determined to tell Ross what she didn't get a chance to tell him in London - that she still loves him. Despite Monica trying to talk her out of it, she tells him, but immediately releases how funny it sounds, leaving a bemused Ross to consider the comical state of his marriage thus far.

Later, on a trip to Las Vegas, the two got married after a drinking binge. Unable to get an annulment, they had to divorce, despite Ross's panic over being a "triple divorcee." Rachel and Ross later had a baby, Emma, who was conceived after a one-night stand, although they chose to remain just friends and live together to raise Emma. Eventually, in the final season, Rachel and Ross finally got together after she almost moved to Paris for a new job.

Monica

The other friend Rachel was closest to was Monica, her friend since high school. In their high school years, it is revealed that Rachel was a popular cheerleader with a string of boyfriends while Monica was her less attractive and overweight best friend. They remained close however, and later became roommates after Rachel ran out on her wedding and went to Central Perk looking for Monica's support in the show's first episode.

Monica didn't expect their relationship to last however when in a flashback episode, a teenage Monica says "10 bucks says I'll never see that woman again in my life".

Their living situation lasted for the first several seasons until eventually Chandler moved in with Monica. Rachel's moving out drew the two women to tears. Later, they had a near falling out when, on the day of Monica's engagement to Chandler, Monica caught Rachel and Ross kissing, and accused Rachel of always trying "to steal her thunder".