When Bert Ellison experienced intense mood swings, the first person he turned to was usually not his wife, but Dan Driscoll, his close friend of more than two decades. During the first year of his PhD programme, Mr Ellison was an emotional yo-yo, one day telling his wife that he wanted to quit, the next that all was well. Mr Driscoll suggested that Mr Ellison take the concerns to him first, easing the stress on their marriage.

“I didn’t make a vow to Dan on my wedding day,” Mr Ellison told me, “but I’m able to uphold my vows, I think, more fully because I can process some stuff with my best friend before I bring a more polished version to my wife.”