There are lots of studies saying varying things. Here are a couple: https://www.marketwatch.com/story/married-couples-are-happier-than-everyone-else-especially-in-middle-age-2019-05-23

https://ifstudies.org/blog/does-getting-married-really-make-you-happier#:~:text=Indeed%2C%20married%20people%20are%20happier,and%2015%25%20for%20people%20who