Which psychologists came to this conclusion? The leading researcher on marriage is Eli Finkel, and he definitely did not come to that conclusion. Very few marriages are happy ones. It's pretty much like winning the lottery. And I say this as a product of two people who were happily married for 58 years

I already wrote about this subject: https://betterhumans.pub/does-marriage-make-you-happier-and-healthier-c49ed38cfd88