Someone mentioned 'third' places which aren't home and aren't work. The church used to operate like this and still does for some people. I used to go occasionally and it would be the only outing many would have in a week. Other churchgoers would take responsibility for visiting those in hospital or house-bound as well, and enjoy the activity.
People who have the time, energy and religious inclination to reach out continually to others are rare these days.
I don't blame anyone, but the loss of community-based places, not just religious, even youth groups, makes people insular. My 16 and 17 year old would do fantastically in a youth group, away from school, but there are none any more.
Being part of something bigger isn't very fashionable, and there aren't the social structures to support it.
On here, lots of people with nice houses and nice husbands are delighted not to return to the office, and can't see why they should disrupt their WFH to go meet the younger members of staff, or those who would otherwise be isolated, or to brain-storm creatively. I also love WFH but I see the value to my students and to the community I work in of me leaving my house a couple of times a week and interacting with them, even though it would be easier to stay home.
You don't think you will be that widow. I have been, and I was so grateful I had a big group of local friends and colleagues to rally me round me in the early days. Without work friends, built up over the years, and lots and lots of friends (as they can't all drop everything, many are also stressed, busy, traumatized themselves), it would have been a lonely time, but it wasn't.
I think it's a mix of no funding or interest in maintaining third spaces, the tendency towards individualism (which is great if all you need is set up in your home, not great for everyone else) and just the pandemic shutting a lot of things down and them taking ages to restart, it's all creating a perfect storm of loneliness for the coming years.