Can’t see what gives your wife cause for concern as men want to fuck real women and she’s got the body to take on several guys at a time preferably in a place where she’s nothing else to do but fuck for some days although if she’s a girlfriend who’s like minded it would be good to have her along as well for the things that women can do with each other to drive the men nuts for them both. Important that you understand fully what she doesn’t want to happen as men in groups can sometimes lose control forgetting that the woman’s there for her own pleasure just as much as theirs so if she doesn’t like being bitten slapped around or whatever it'll be down to you to enforce her wishes.
Get her out of the domestic environment for two of three days at a time each month, more if you can manage it so she doesn’t have to deal with everyday matters and have her enjoy orgasms cocks and cum, she’ll adapt to it they all do as it allows her to be the sex goddess to a group of men and the more she has the more she‘ll want with growing sexual confidence. She’ll need ...... and rest so set up a timetable for her and each evening if you’re away from where people know her get three or four of the guys to take her out for a meal and a few drinks, not too many as she needs all her senses to enjoy fucking it’ll be a small change for her, don’t go yourself let her enjoy their company and I’m sure they’ll keep her amused by touch and most probably fuck her in the car on the way back to the group in readiness for the evenings pleasure. She’ll change no question of that but it’s a change you both need to fulfil your desires.