For us it was 15 years ago, my wife takes a very long time to get reved up but when she does she is like the Energizer Bunny and honestly sometimes I would be well wasted and she was still going, we had a large toy collection (which I love watching her use) then thought we would try a third guy and BAM she was blown away and I guess a little shellfish on my part I could get a break and watch and play, she got all she needed and so did I .
We have never looked back since, we play with couples as well but two guys is till her fav. Next thing we want to try is a small gang bang.