My first husband cheated on me, so I am going to be quite judgemental because I feel I have the right to, having been involved in that experience. I have no respect or use for him. Neither does my daughter. He left the woman he was having his last fling with for someone else. I think (and I told her) that she's an idiot for marrying him, knowing his track record, and his values.
Both parties you are talking about are wrong because they have marriages, may have children, parents, friends, etc. Each one of these will be hurt by the affair. If a marriage isn't working out, they should be mature enough to either work on it, or leave if they can't work it out. Once people are single, they can do what they want.
I suspect the age difference has something to do with the relationship. There's
nothing wrong with it, but put that together with this being a long term affair, it doesn't sound like a stable relationship.
I also can't imagine why 2 people with families would waste their energy on all of this drama. Life is way too short, and it really sounds like both lives are way too complicated by an unstable relationship.
He never said he loves her? He sounds like a real loser!
It sounds like a demeaning, boring, negative waste of time to me.