If you ask me who kept the group together, as one single unit, supporting one another, It would always be Phoebe. She’s the sweetest. Though she was annoying in the beginning, she aged gracefully into being the sanest soul in the latter half of the series.
Phoebe was more of an outsider. She was a non-roommate for most of the time. However, Phoebe was crucial to the group. Whenever the group was on the verge of splitting, it was Phoebe who stepped up and kept the group together.
In any dire and critical situation, it was the same crazy Phoebe who was the voice of reason and the one who babysat them all.
Few are some instances that show that Phoebe was a true unsung hero of Friends. This will be a nice trip down memory lane.
https://www.youtube.com/watch?v=TUVXVM4CJIM
https://www.youtube.com/watch?v=U_jA2AvKQfU
https://www.youtube.com/watch?v=yDDQZJPrbpM
She grew up in an environment where she didn’t really have a family. She’s struck by her mother’s suicide, her father abandoning her, her step-dad in prison, and her twin sister who’s not on talking terms with her. Hence, she really valued her friendship and never let that breakup, no matter what. Reason, logic, or force- she did everything that was required to keep the friends together.