I have been critiquing studies like that for nearly 2 decades, and also discussing the newer ones — at least one of which has been ongoing for decades. Here’s a whole collection of my writings, just on health:

Getting Married and (Not) Getting Healthy: What Decades of Research Really Shows

Look esp at the first two but all the others are relevant, too.

If you want more than just health, here are hundreds more articles I’ve written:

What We Really Know About Single Life

That one begins with an opening paragraph that mentions a book that is relevant, too.