Does she go to dinner without him?
I doubt it very much.
You have changed the parameters of the discussion. I'm sure that she goes to dinner without him and he goes to dinner without her.
The issue is going to dinner with a member of the opposite sex who might be perceived as a romantic interest and with no one else along, i.e. 'a date'. If I am at dinner without my wife and with another female only, I am not "living dangerously" if that 'other woman' happens to be my mother or one of my daughters.
A person of responsibility, whether a politician or merely a husband (or wife), needs to "avoid the appearance of evil". You know, like Bill Clinton's airport tarmac meeting with Loretta Lynch?