Psychology Today was a PC pile of dreck 20 years ago and it hasn’t changed. It puts on a nice colorful smiley cover now and is sold on newssstands everywhere but the a priori conclusions are just as prevalent, despite (all together now) science’s aim to be dispassionate.
The big error that the author and the psychologists both make is in assuming that sex is the main reason why all couples get together and stay together. While, I would agree that this certainly holds true for gay couples, it is far less so for heterosexual ones. Successful normal (heterosexual) couples stay together because sex is only a part of many factors of a fruitful relationship.