The only advice I can give you after years sharing my partners is do not rush it.. Take your time finding a guy and remember that you both must like him, nothing worse than having a guy you don't like fucking your GF/wife......
..
..
Be very aware of your wife's feelings toward the other man, coz distrust always makes jealousy and if you or your wife are unsure stop or don't do it! And be very clear BEFORE you start that both of you can end it right there and then, with out any excuse or explanation.. You can try another time, no sweet.... .. .. and nor you or your wife shall ever do it bc of the the other partner want's to do it, you both has to be and feel safe in this..
If you never have seen your partner fuck another man you are in for some really horny stuff too watch.... If you have the stomach to watch it, coz it is really strong stuff..
Be also very clear where the other men can cum (in her mouth, pussy, ass......? ), use of condom is vice at first even if you like sloppy seconds.. And don't be alarmed if your wife totally freaks out or having an orgasm and suddenly turns a little kinky with the other man, it is normal if she turns on by it.. You will probably see sides with your wife you didn't know existed.. My wife shocked me a little when she agreed to her lover peeing on her in the shower, sometimes even in her mouth before they flip and she is peeing on her lover.. It was a kink I'll never have seen before and didn't even think of to be honest.. I have tried, but it did not give me anything, but I like to watch her doing it but that kink is something she and her lover is doing in the shower without me.. My wife also get the biggest orgasms when her lover fucks her ass for some reason.. At first it made me very jealous, but today I love seeing her get off with his cuck inside her, I love seeing her having a great time and know that she is extra aroused when she know her lover comes over to fuck her, so it is normal....
..
And remember, this is just for fun.. So don't let it turn too serious before ending it!
..
..
My wife and I used about 7 month finding her current lover (in a hot tub at a naturist resort......), my wife liked him at once but I was thinking the age gap with his almost 16 years on my wife was a turnoff at first, but at the time he finger fucked my naked wife down in the hot tub water late that night I liked him.. It was a little shocking for me that my wife decided to spend that night with him (we had planed it, but but but......), but I went with it and when she came back to our rented cabin the next day, just as naked as she was when she left, she was a very happy women after he have fucked her three times that night.. She had sucked him off before they went on a night bath on the beach in front of the naturist camp, where he started fucking her pussy in the water before returning to his trailer where he fucked her pussy until he came in her , then they slept together and then, right before she got back to me, he had fucked her ass.. So it was a very happy and well used wife I got to fuck when she came back to me and I loved it.. He has been her lover for 3 years now and we both enjoy him fucking my wife on a somewhat regular basis...... The best part is the great sex my wife and I have in the days after her lover had visited us...... We both love that....