First, you need to tell them. Making something up like "taking time off" will backfire when they run into you playing with others. They will ask again to play and you are back to square one. Adamgunn's approach is the best one. But also realize the just being friends is most likely not going to work out since the other couple will only think of "rejection" each time they see or get with you on a friendly type basis.
And don't lead on with sexy teases after you told them. We had a couple we really liked and played with a number of times (we were their first couple in fact). But they gave us the "we just want to be friends now" speech. We were glad they told us and respected that. But then, each time we would see them, he would go into a deep passionate kiss with my wife like nothing changed. I told her to not respond to that and not allow him that kind of kiss. Friends don't do that and they can't have it both ways.
We have moved on and you should too.