My wife has had a man on the side for a couple months and they refer to one another as boyfriend/girlfriend and it’s been working out great. All three of us have been happy with the arrangement but I have discovered a feeling of jealousy that I have not anticipated. I feel like his involvement has made me a better, more attentive partner and I don’t mind the sexual things she has shared with him. It feels stupid but hearing him call her pet names or seeing her share pics/memes that have normally been for me has brought out a jealous feeling that is new. I don’t feel threatened at all and I feel like it’s going to benefit us eventually