Just curious about this type of situation


So my fiancé has a best friend and they are in a fraternity together. He graduated and moved to Cali and his gf at the time stayed back to finish school so they had a long distance relationship. A couple months later last summer our other friends that are a couple and have a one yr old together started fighting a lot and she decided to leave for a couple days with her son so the bf could relax and while she was gone we heard that the gf of the guy that left to Cali hooked up with the guy that had a kid with the other girl. Only a few people know me my fiance and another couple but nobody else knows. The guy with kid is back with the girlfriend and now she’s pregnant with baby number 2. My fiancé told me not to say anything to his friend about it but it’s bugged me not to say anything especially now that he’s coming in town to see my fiancé graduate. Is it right for us not to say anything?