I found contentment in my life probably a decade ago, maybe longer. I gave up worry, have no stress and do nothing that will create either. I have led an interesting life, seen much of the western world, had love, passed on my genes to the future with my son and grandsons. I have little I need, less that I want at this stage. I am open to the possibility of being with someone, but not obsessed with the idea. I take life one day at a time as it comes along, and that works well for me.

I think you are right.
In reality a good marriage, family and life well lived can be far more satisfying the the desire and hunt to attain them.
I have been happily married for over thirty years now, and I am both happy and content with my life, have achieved most everything I ever set out to find and achieve.
However western society, especially US social conventions continually pounds people from birth with the myth that the grass is always greener, success is not success if you do not get everything that you want, that not winning is utter failure and that being satisfied is a weakness.
Hence soaring debts and divorce rates, the desire to stay young forever, elective surgery and medication use and the constant depression caused by always wanting the new and the better and having to struggle for it lest you be found wanting.
All for the unwitting financial benefit of the peddlers of the problem myth and the easy solution

A little ambition is fine, the writer who wants to write a another story, the artist who struggle for greater realism, the musician seeing a more beautiful melody, the parent wanting happiness for their child.
This is perhaps the sentiment and "wise desire"Tennessee Williams was attempting to convey?