In my late 30s now and seeing a few of these things pop up in my peer group and beyond. One I know the the husband cheated and even briefly left his wife to be with the OW before sobering up to what the reality of divorce with two young children would look like. In another that particular marriage was the man's second and they started as an affair while he was still married to his first wife and he has a career that would give ample opportunity to cheat. Others I'm not sure but wouldn't be too shocked it that was the case.
Personally I don't see the point of it at all. It seems quite crass and attention seeking. Quite a few have been really expensive, essentially a wedding again with a sit down meal and evening reception and must have cost £10,000 + which seems like a tremendous waste of money. Then there is the gifting issue, some ask for no gifts but increasingly I've seen gift registries for vow renewal's which feels grabby.
To me I just think have a big party, make a speech if you want to proclaim your love to each other in front of your friends and family but renewing your vows in a faux marriage ceremony is either pointless or its because you feel those vows have been broken.