What would you do if your spouse, significant other, good friend or girlfriend told you that they wanted you to watch them having sex with someone else?

Be a very happy man!

I would have no trouble with my gf and another girl

I'd do it in a heartbeat with her HOT blonde g/f.

Cuckquean fantasy, I like

Beg her for a three way outing

Kinda actually happened only I was the one asking for her to have sex with another guy. Worked out pretty hot sexually but its like playing with fire when girls have sex with another guy.

Have sort of done it. It was hot at the time. Afterwards I regretted it.

Did it years ago,absolutely loved it and want to do it again.

What would i do? Get down on my knees and thank God!! Did it three times with one male friend 25 years ago. Only thing better than fucking another man's wife is watching your wife get fucked by another man. It is wonderful. Beautiful sex thoughts, lots of jacking, and ready to fuck your wife for weeks afterward.

That has happened and we have done it. many times. Love it every time. Swinging is fun

Super stoked with a smile and a boner!

Too right it's playing with fire. Same if she asks you to be present while she has sex with a woman.
It's a plus -- that she asked you to be there. That makes it open, and you are not just pacing the hall until she comes out of the bedroom with her lover.
It's a minus -- that you'll never forget the sight of her lover, in action giving and getting, right there, and you'll either 'want' that lover in some way in the back of your mind or hate him/her for a long time. Probably this isn't something you would have chosen.
Outcome -- she may be really hot for you afterward, or not, but the fire is lit and you said it was OK and she'll never get over the threesome if it was good at all, and she'll be mentally back in bed with that lover a lot, and maybe physically too.

If everyone is joining in then its all good. Had one MMF with an ex and i'd do it again in a heartbeat.

I've been begging my wife to fuck other men for years. I'd love knowing her tight little pussy was getting used by someone.