I'm sharing a success story:
I struggled with mental load and I resolved it without saying a word to my husband. Disclaimer: I know my circumstances were unusual. So what happened was that my husband agreed to care for our 1 year old son by himself for a total of 6 months this year to allow me to finish my Master's abroad. The shortest span was 6 weeks and the longest was 3 months. I got back in October and we've since discussed mental load as something I bore alone in the past. I was so happy to hear my husband doing mom math as we prepared to get to an event on time. He now appreciates the importance of being efficient on a morning because a 5 minutes now can make you 30 minutes late for work. He now takes the initiative to prep meals the night before and doesn't waste time playing with our son or watching his phone on mornings. There are no words I could've used to give him a deeper understanding than living it for weeks at a time. However, he has also admitted that it was extremely important for him to decide to take on that challenge without being pressured by me. Otherwise, he might've resented me. Instead, he said that because he chose to do it willingly, even if he wanted to blame someone he would only blame himself.
So maybe this is a challenge to the men. Would you be willing to send your wife away for a week to truly walk in her shoes? I'm sure she would appreciate the break and you would both be eager to share the mental load more equally when she returns.