The thing I don't understand in all these discussion is I know a fair number of men in long term-- and sometimes happy-- relationships. They aren't high-display of masculinity guys, and yet,

Are these mostly older guys or more precisely guys in LTRs with older women?

The increase over the last 4 decades in female personal income has made the "beta good provider" male strategy less successful.

Also, some (e.g., the Man Who Is Thursday) say that the increase in female promiscuity has had a similar effect because (the thinking goes) once a woman has had sex with 1 or 2 extremely exciting men, she is less likely to settle for a LTR with a much less exciting one (and as long as she does not demand any sort of commitment from them, a woman using a "modern" sexual strategy will probably have sex with 1 or 2 extremely exciting men).

Although I have a relatively small circle of friends, even I have a friend of a friend, now in her 60s, who only ever had sex with one man (the father of her kids to which she is still married) and she was quite beautiful, grew up in the proverbial big city (Manhattan) and has and had no notable social handicaps.