Hello, here is my insight as the "extra guy". First, I sense that you are not quite comfortable with alone time so I would not have that happen. If you are ok with alone time, sometimes it is better for the guys to be alone first. I have had some very interesting conversations with the husband that were very helpful...like, she really likes this....if you want to squirt,do this, are you good doing?
She really gets hot and wet etc etc. If there is only alone time with the extra guy and her or you start to feel left out, have a code word between the two of you. Establish trust slowly. Us guys know we are less than a dime a dozen.....Yep. It pays to be a humble guy.
The more experienced I get, the better I can read both the wife and hubby. Are they on the same page? If not, I normally say something like "you are both very attractive but I don't want to create any drama so I am stepping awhile" This is never done DEAR JOHN style but more like I apologize for not creating "the magic". I enjoy MFM because DVP is so awesome and you all need to work together and trust each other for that to succeed and when it takes a few tries and everyone laughs, you know it is good. I hope that makes sense. Please let me know how it works out and if this was helpful.