My office is a very friendly atmosphere although we are all very hardworking. It’s a county government office by as a whole we are all friends, often hang out outside of work, have been invited to each other’s weddings, etc. We have one inter office couple and despite the friendliness no affairs that I know of in the 10+ years it’s been this way. Since I am a firsthand witness that yes, men and women can indeed work together and be strictly friends, I have no issues with my DH being friendly with others and he has no issue with me either. His field of work overlaps with mine and he is friends with my co workers, even the females. There have been times they/we text jokes, etc., one on one, and it’s been totally fine. Never anything I wouldn’t show him on my phone if he asked. But we trust each other and aren’t threatened by anyone else. If you have a healthy relationship with trust and respect, I disagree with the DCUM default position that opposite sex friendships are predisposed to becoming affairs. That’s the position of a person who is insecure, threatened, and lacks trust in their partner.