"There's absolutely no judgement in Court," Jennifer tells the February issue of More of cover girl Courteney. "You'll never feel scolded. She's extremely fair, ridiculously loyal and fiercely loving."
Jen, 44, and Courteney, 49, have been close ever since they started working together on Friends two decades ago. Since then, Jennifer has gone through a painful divorce from husband Brad Pitt, while Courteney ended her 14-year marriage to David Arquette in May last year.
"I've slept in her guest bedroom a lot," Jennifer revealed. "Without giving away too much of my private stuff, all I can say is she's been there for me through thick and thin."
Friends co-star Lisa Kudrow, 50, was equally effusive in her praise of Courteney. "There's no agenda. There's no guile," she told the magazine. "You can trust her completely and fully.
"Whether I see Courteney every week or once a year, it doesn't matter. I know who she is, and I know where I stand."
Courteney's loyalty is evident in her relationship with ex-husband David, the father of their nine-year-old daughter Coco. The actor is now expecting a baby boy with girlfriend Christina McLarty, an Entertainment Tonight correspondant he's been dating for two years.
"When you love someone, you want them to be happy, even if it's not with you," the actress, who will be 50 in June, told More. "Obviously, kids always want their parents to be together, but as divorces go, this is the best one we could provide."
The couple were married in 1999 and separated in 2010, although they did not finalise their divorce until May 2013.
"In divorce you always have regrets," Courteney added. "We were married for a long time, so it's not like we didn't try."