That isn't really true.
https://www.yahoo.com/news/fact-check-posts-claiming-40-110000305.html?guccounter=1
The Neidig study stated in its abstract, "Survey results revealed that approximately 40 percent of the participating officers reported marital conflicts involving physical aggression during the previous year." However, that "physical aggression" included violence perpetrated by the officers' spouses. The results for violence perpetrated in the relationship in general was 41% for male officers and 40% for female officers. Importantly, Neidig's results for violence specifically perpetrated by the officers against their spouses were much lower: 28% for male and 27% for female.
So 28% is the number, really, and "physical violence" is not necessarily the same thing as "beating their spouse." That could mean shoving them, or pulling their arm or something. One criticism of the original study is how vaguely it defines "physical violence".
I know I will be labeled as a bootlicker, and I swear I'm not, I just don't like misinformation and on lemmy all the misinformation is leftist. On PCM on reddit I spend my time calling out conservative BS.