Speaking as a man just entering the multiple partner phase of a relationship with my wife of 15 years. (She is the one who initiated our path into Polyamory).
I absolutely HATE the "It's a guy thing." trope and I hate even more when guys buy into it!
It completely dismisses the fact that we as guys DO have emotions beyond our favorite sports teams and it encourages guys to just "tough it out".
I have watched a number of friendships and romantic relationships between other people disintegrate because of one reason. People don't talk and when they do they do not say what they really feel.
Now, my marriage has had it's ups and downs but throughout it all we have both striven to be as open about how we feel as possible. My wife is the person I trust above ALL others in my life and I know that I can tell her anything with honesty and no matter what it will be heard and an honest attempt at understanding will be made. She knows the same.
We have not really entered into the multiple partner phase yet. She has found another woman whom she can meet up with within a few hours drive. They have become emotionally connected through internet contact. They are meeting up in a couple weekends for their first meeting. I think that we will be okay because she shares her concerns and fears about this new relationship with me and I actually feel supportive in this.
Having a long distance relationship like this is not the same as what you are experiencing. My wife does not need to act the "hinge" because this other woman is not (yet) physically present in our daily or even weekly lives.
I like to think that once she is (I am assuming something will happen to make this possible if their relationship deepens as they hope it will), I will be just as communicative with my wife's friend as I am with my wife.