Literally zero of the things in the author's marriage are necessarily attributable to the marriage itself, or necessarily consequences of marriage for that matter.
And never mind co-habitating, all of the transformative stuff could have happened regardless while simply living with an upbeat roommate.
"The case for living with or near positive people that share similar ideals" probably wouldn't get as many eyeballs, but it would be more to-the-point and true, I think.
Maybe I should write that article anyway. I've had roommates literally my entire life, sharing a room with my brother until college, then dorming with one guy, then seven people, then two guys, then three girls, and now that I've graduated I live in a huge victorian-era house and rent to three friends (my "rent" therefore is free, sans house upkeep). I've been fortunate enough to never have a bad roommate, and communal living can be a lot of fun, significant other or not.
I think living and working alongside loving and caring people is great, but I think restricting it to marriage is maybe a tad myopic. I love all micro-societies and think they have very similar values.