Blade ~
In your position, having your very good friend asking you to help her convince her husband to do something he doesn't want to do, you risk getting wedged in a very tight spot that may leave you feeling stuck with a situation you regret getting into.
As a friend, you should offer
some help, but be careful she doesn't start relying on you to do the communicating with her husband that she doesn't want to do. You know the kind, "Talk him into seeing MY way, please!"
You said she's not a reader, which concerns me. How does she expect to learn about swinging without being open to various resources, besides calling on you?
Ultimately she and her husband need to work this out between them.
I guess what I'm saying is don't get pinned between them or you may lose a friend. Keep a safe - but supporting - distance.
LM