Lurked here for the last few months and only recently had reason enough to introduce myself!
My wife (A) and I have been together for 11 years, but married for 7. We have three kids aged 8, 11 and soon to be 16 - hectic house! I'm 31 and my wife is 36.
In the last few months, we have discussed opening our marriage up. Both of us have done our best to look at as many potential problems as possible and even reiterated that neither of us wants to split up, divorce, etc. We do love and value each other too much to want to lose what we have!
As you can guess from my username, I'm the monogamous one in the marriage and my wife has just recently got involved with a 24 year old guy (S). I'm probably one of those rare examples of people who've only ever loved or slept with the one person - literally. My wife was married before me and had also had a couple of relationships before then too. Our marriage is the longest relationship she's ever had though.
What she's told me she wants is to stay married to me, but also wants to see S occasionally. Something extra and a friend with benefits type arrangement. I should mention she had sex with S for the first time a couple of days ago with my knowledge. The various threads I've read here has helped me deal with this situation better than I probably would have. I also have "Opening Up".
We're at the point where we've realised that boundaries need to be better established due to S's lack of communication skills. My wife has always had great communication skills while I've had to sharpen mine!
I guess this is to say "Hi!" and there's a few things we will likely pick your brains over!
We are also in the UK! I know a lot of members here are from North America.