I agree, using a toy is what me and my wife have been doing, with enough imagination and enthusiasm it handles the job, and the best part is, nobody to feel awkward after the blood returns to the brain from the groin!

Most guys do have hangups on the mmf thing. There are unfair double standards big time with mmf vs mff, at least in the US. When most people think of a couple having a 3way with another girl, most think that woman has to be so confident and sexual to invite a woman into bed with her man. If the couple adds a guy, most will assume that the guy is a wimp, or cant get it done in the bedroom, etc. the whole cuckold culture. I think that in a secure relationship, if you want to "broaden your sexual horizons" , if either one of you is bi or curious, then that seems to be natural 1st threesome, so if a couple has a bi F, only, then adding another woman seems logical, whereas if the M is bi or more open to being bi, then adding a man makes sense. If neither of you are bi or curious, it is a bit trickier, as the guy will get nothing out of a guy joining and a woman will get nothing out of a woman joining. Dont know what to tell you there. :)

For me, I have had bi experiences over 12 years ago, with a friend, and think of them often, but my wife hasn't experimented with women (so she says hehe)... Therefore she would be more comfortable adding a guy first. If she enjoys it and it makes her feel sexy to be desired by 2 men, she would likely be confidant enough to try a couple or single female after that.

the key is open communication, trust, and making each other as wildly happy and fullfilled!

hope that helps