Clint did change partners like socks, but Bob434 might be talking about Eli Wallach, who was married to one woman for 66 years until his death in 2014 (at 98!).
Eli had a cameo in Clint's Mystic River in 2003, one of his last roles.

Clint directed “Breezy”, where William Holden, who was like in his 60s, had an affair with an 18-year old Hippy Chick.
So I always suspected Clint is a bit of a libertine on some things.
Yep- i was talking about Eli- The article i read on him didn’t go into specifics about his personal life other than he loved his wife and stayed married for 66 years- he mighta had partners outside of marriage, i dunno- but it’s kinda remarkable that they stayed together so long- remarkable for hollyweird i mean
Wallach was a great, underappreciated character actor. Westerns, mafia, you name it; he made his character utterly convincing.