I agree, openness, full communication and honestly are the keys, she may embrace it and what women wouldnt, but for you there maybe jealousy ahead about her enjoying her lovers sex more than yours. Once started and enjoyed its unlikely she will stop.
Its also likely that should she find a regular experienced lover that flicks all her switches, you become overtime become her secondary lover, or surplus.
There is a lot of emotional attachment having sex with another man for her, unless they are to be one offs. We have always prefered long term lovers.
We have lived the lifestyle for pushing 40 years, we did start rather young though when she was 17.
But remember it is a dangerous game you seek to play and these boards whilst positive are littered by disaster and divorce. Few posters tell the stories of disaster just disappear never to be seen again.
Good luck.