[Josy]

Decent honest married men (or even men that are in a long term relationship) tend have no need for a mistress, I think happily being 'the mistress' in the situation says a lot of that person, they have no respect for themselves and are clearly someone that happily plays that part without feeling or guilt for the other parties involved and not just the wife or other partner but for the rest of the families too including children.

Mistresses are generally kept secret for a reason too, they are used by the so called men they get involved with and then flung to the side and ignored when it comes to more important things in the mans life like his wife and children.

I'm only replying to the husband/wife scenario due to whats said in the OP but do find the topic to be slightly sexist as it's not just men who have affairs so what I said could be applied to anyone.