The One… (You get the idea.)
And for co-creators Crane and Marta Kauffman, that came from experience.
(Aside from their regularly scheduled trips to Central Perk, of course.)

NBC
So it’s no surprise that, from time to time, the writers drew from their own experiences.
Such as thestory that’s been toldabout writer Adam Chase buying a pair of leather pants.
“You’re just trying to tell funny stories and have it work.
There was never an eye toward, ‘Wow, this is an iconic moment.'”
But once filming started, the answer was an obvious “yes.”
“Even on stage that was fantastically funny,” he says.
“At least once on the show space was a problem,” Crane jokes.
That’s New York.
That’s where we captured the New York we actually lived in."
(Remember, he’s her lobster!)
“In the pilot, they’re a thing,” Crane says.
People had stuck with us for 10 years, they had to end up together.
And hopefully we got that when she gets off the plane."
“We weren’t really guest-star driven,” he says.
“We didn’t write episodes for people.
Are you crazy?!’
I was always surprised and delighted.”