Hello,
I watched the series as well. It's hard to classify the young lady as the OW as he was divorced when she was introduced as a character. However, Nick showed all the characteristics of MLC plus. He had already cheated on Anne in the past and he was very self absorbed in the relationship with Ginny was more about him and his feelings. This idea or notion of "You made me happy" or "You made him happy" is the false narrative of a sound relationship. It's the myth of eternal happiness. You noticed that Anne never stated that Nick made her happy. Instead, she mourned the loss of her role as "I am the person responsible for making Nick happy". In the end, it wasn't that Ginny and Nick were is a sound relationship. Anne just acknowledged that Ginny met the job requirements of "Making Nick happy". Nick even tried to keep the group together for his satisfaction and when he was with Ginny's friends, it wasn't that he was dealing with a generation gap, it was an interest gap. Nick wasn't really interested in her social group.
Nick's daughter called him out on his self absorption because after the play, he was angry that she challenged the role of the wife's role to bring happiness to Nick. He rage at her was because she didn't get the memo that his happiness comes first- even if it is at the expense of everyone else.
The other two couples were also very interesting. Claude and Danny also created the dynamic of the role to make someone happy. Claude was well meaning and very protective of Danny. However, that only created resentment and distance by Danny. The classic line was when Danny complained to Claude. "It's just sad, can't you just let me be sad?"
Kate and Jack were dealing with their own issues and Kate had a lot of contempt for Jack. In many circles, contempt can kill a relationship faster than an affair. However, they were able to reestablish themselves at the end.
Overall, the series was good, but at the end, it fell for the "soul" mate notion that I completely reject as another myth. There are over eight billion people in the world and this idea that there is only one other person in the wide pool that is the one for you is ridiculous. I guess some parents are very good at finding these "soulmates" because divorce rates for arranged marriages are lower than find your own person.
Just my opinion and have a great day,
(((Ready)))