Quoting Tarynosaurus Rex:" Why does it suck if it doesn't affect you?"
I had a HUGE post asking this same thing, but decided not to post it. If a couple is happy with a monogamous sexual relationship, great. If that's what works for them, wonderful. But seriously smurf off with the judging of others who feel differently and have different relationship dynamics.
I personally think it "sucks" for them because they feel that everyone should live according to the morals set out in their
bible by their
god. Since not everyone agrees with that and most are of the "live and let live, but it's not for me" opinion, this somehow makes it seem to them that the world is going to hell in a hand basket and that they are in the minority. For some reason, being in the minority makes them feel persecuted simply because others disagree with them. Martyrdom at its best, even though no one here is actually saying their opinion
is wrong, simply that the way they are going about stating it is wrong. You can say "No, I wouldn't allow it. I'm uncomfortable with the idea" and leave it at that instead of throwing in words like "disgusting", "nasty", and questioning the strength of someone's relationship. The OP asked "Would you", she didn't ask for judgment of those who would.