I am suggesting that some of the empty feelings around retirement are analogous to some of the emptiness reported about women in feminist texts of the 1960s.
The Feminine Mystique by Betty Freidan (1963) has in it poignant accounts of how some well-educated women (some who had had meaningful working lives during World War II) indicated a general unease with their lives. Women's work in the home (for various reasons) was seen as less meaningful and valuable in previously. This led to a loss of social identity and a feeling that life was meaningless or empty, even where the women had ideal homes and children and husbands. Women were trapped in a social situation that did not reflect the reality of post-war opportunities. Other writers, in other ways, express similar bleak pictures of women's life and labour.
Retirement seems to me to have some of the same characteristics both for men and for women. The details are different - the outcomes are different.
The analogy is helpful in energising and raising expectations of retired people - especially those who have retired before they feel ready. And it may be that it is a way of interpreting the horrors of retirment and old age.