OK, I have to chime in here. My wife and I have done this. We have had MFM and a FMF threesomes. They were great for us even if it has been several years since we have done this. It made our strong relationship stronger! We had been together for a round 12 years or so and started really talking about our fantasies. I told her I would love to see her with another man as long as I was somewhat involved in it all. We used the fantasy in our sex life and had a lot of fun with it. We started talking about what if it really happened. So, we started reading about how people go about doing something like this and how to set rules and avoid jealousy. We did a lot of talking and researching before we even looked for someone else. We knew we were doing it for fun and nothing more! Sex is just sex! Making love is what we do alone. The first time, the other never penetrated her, just oral. That was fun and we decided to try more. The next was the FMF. I never penetrated the other woman, just oral and it was also fun. She got to fullfill he bi side! We had a friend that was going through a bad divorce. We had talked about him before and thought he might be up for some "fun"! He was over one night and the 3 of us were alone and we turned the talk to sex. We talked about all kinds of sexual things and I finally ask him if he would like her to give him a blow job. He said hell yeah!! So, she goes over an blew his mind! He left a little bit later and we ended up having incredible sex that night and well into the next morning!! We both enjoyed that very much! A few weeks later, we had decided we were going to get a hotel room for a night with a whirlpool tub. We never really talked about him coming with us. We got there and the tub was huge and we both had the same idea, let's get our friend to come over to the hotel. So, I called him and told him what we had on our minds. He was there in a flash!! That was the first time anyone else besides me had penetrated her! It was amasing for all of us. The 3 of us had sex all night until a little before checkout! She was sore for days, but had a smile on her face that you couldn't scrape off and so did I!! We continued to have fun with our friend from time to time. We finally decided that we needed to take a break from doing this so he might be able to find someone to be happy with. We are both happy that we lived out these and it has made our relationship and sex life stronger! We have NEVER thrown anything in the others face, but we do still talk about it from time to time. We are not against doing it again, but we are not forcing the issue, either. We are happy with each other and if it happens again, we know we can handle it! It isn't for everyone and we have seen it split couples apart. You have to be very secure in your relationship and neither can be the jealous type!! So yes, it can be a great fantasy that needs to be kept a fantasy, but it can work out if you both agree on everything that might happen. That is the biggest thing, make sure you both know and want what might happen. Some of us can and some of us can't. That one is for everyone to figure out with their SO's! It worked for us, though and it was a blast!! Peace, Mark