I can only put this from my point of view (a husband) and assume that the female (wife) would feel much the same way:
I would hate the thought of my wife being intimate with someone else, male or female. If it had to happen, I would rather not ever know about it. But supposing she wanted to go out and have sex with someone at a pick up place (or anywhere) and I told her it was OK. What would I think about while she was gone? What would I ask her when she came home? "What did it feel like?" "Did you enjoy it?" "Did you (use your imagination, some things aren't appropriate for this forum) to her?" "Did she .......... to you?"
I guess I've become "old fashioned" as I've matured, but to me, some things are sacred and sexual contact is one of those things.
