S.W.
I divorced my husband when I was 46 and he was 52. We'd been together for 23 years. We have two children from his previous marriage that we raised together. I didn't expect anything from them except for them to not judge my decision(s). Listening without giving advice is also a great trait to have in this situation.
They are grown-ups, and yes, just at "mid-life", so let them be. Unless they specifically ask for help, just be a good listener, and offer to get together with them once in a while if you live close enough. They may need to reminisce about their marriage for a lot longer. Starting new relationships may or may not be what they need so soon, so let them decide that.