We are 20 years older (early 60s). Virtually none of my friends around our age have split up (though a couple of the husbands were married before my friend met them) and neither have the (generally a bit younger) parents of my children's friends (though again some were previously divorced or single for as long as I've known them).
Mostly we met late 20s and married in our early 30s so had 'played the field' before settling down which probably makes a difference. Also getting divorced wasn't quite so accepted when we were younger maybe.
The pandemic did make me rethink my marriage though. I never really questioned it until mid my 50s when we had a landmark anniversary and I wondered what exactly we were celebrating. But seeing my DH fuss over the pandemic made me very irritated with him and wanting to avoid him as much as possible. Luckily I was able to work in my usual place of work throughout, apart from the first couple of months.
Our 30s (mine anyway) were blighted by infertility so when we had kids in our 40s, I was just happy to be getting on with being a parent. DH is a great hands-on parent and with the needs our kids had there was no way I wanted to be a single parent. But we did neglect our relationship a lot. They are young adults now but still living with us. Youngest has mental health issues so their needs still take priority over ours to an extent, though things are improving.
We have made more conscious effort to do things together for ourselves recently and my feelings fluctuate - sometimes it feels fine, sometimes I feel bored and irritated again. We are planning a major piece of work on our house and I sometimes find myself thinking, why bother when we could sell up and buy our own separate places.
But I don't really want to be alone, can't imagine dating at my age etc. DH and I enjoy a lot of the same things, talk non stop when we go out alone together and he is a good person. I suppose we should go to relationship counselling as I do feel there is something to salvage. But if I was 30s / 40s now and childless, I'd probably just leave.