His name is Gerry Goffin, and among others, he wrote the lyrics to Will You Still Love Me Tomorrow, that was a hit sang by the Shirelles, and The Locomotion, originally sang by Little Eva, and much latter made a huge hit by Kilie Minogue. He was three years older than her.
Since Carole also had three more marriages, I think it is more an issue of their respective ways of being, and less a quarter-life case. Maybe also the way many people were, and behaved by then in the arts & culture world. Drinking, drugs, sleeping around were all pretty common. Nowadays musicians and composers are much more clean than they were back in the 60's and 70's.
Just because someone is a troubled soul, think Hank Williams and his reckless life, does not mean one is having a quarter life, or a midlife crisis. At least I do not think so.
I think we never mentioned Richard Gere, who has been dating a woman half his age, and wanting to divorce his wife. Maybe he is finally divorced, I don't know, but the whole things was a mess.
Sometimes good things fall apart so better things can fall together. (Marilyn Monroe)