The first counter-example to this statement that comes to mind, among others, is Brett Weston. He married and divorced multiple times, and none of his wives were crucial to his work. He simply kept producing great photographs through it all.
Hi Mike, hope you are doing well, and the Amidol is still working.
Brett was married four times; I attended his last in 1969. However, prior to that, I would have to say that his marriage to Dody in 1952 had a strong impact on his life and work. He admitted it many times, and they remained close friends until the end of his life. The last time I saw them together was at his 80th birthday celebration in 1991, the morning of which he threw a few negatives into his Carmel fireplace for the benefit of an international press.
To your point, photography always came first for Brett, something he made clear; not a formula for longevity in a marriage. Agreed, his production of great photographs was astounding!