It doesn't always work out.

You are going to find that not every couple you meet is going to be a couple you want to fuck. One of the ways we meet potential new couples online is thru adult swinger sites. You can read profiles and see pics and then decide if you might want to meet.
We recently corresponded with a couple for the better part of six weeks before we were able to coordinate schedules and get together for drinks. They weren't married, but were in a committed relationship and had been for over 18 months.
We finally get together and the evening seems like it is going great. At the end of the evening - they just bow out and we never hear from them again. So sometime it takes awhile to find couples that you click with.