I guess a "wide age gap" needs to be defined. When I was growing up in the 1950s, my grandfather's sister was married to a man 15 years younger than her (unusual for the times) and it was quite a matter for gossip in the family, it was a lasting relationship, she was in her late 70s by then. They never had children.
Two of my friends who are in their mid-sixties have husbands who are 20 years older, in long-term relationships, and so far so good.
Quite a few well-known people have a marriage or a relationship where age doesn't matter - Amanda Redman, Barbara Windsor, Joan Collins to name just a few all have much younger partners.
Actually come to think of it, one can end up being a carer at any age or stage for a spouse.