Yeah, we do tend to be that way. Cops have a hard time relaxing around anyone but other cops, and there are several reasons. One, we get so used to having to watch our backs and never knowing who wants to hurt us that we have a hard time letting our guard down. We also worry that everyone is watching us, and if we cut loose it will tarnish the image. We’re trained from Academy on to always cultivate respect, and we’re afraid to lose that. That worry is reinforced because we’re the only people who are introduced at parties by profession (“This is my friend David. He’s a Seattle cop.”)
My Police Association used to have an annual holiday party and invite the prosecutor, court staff, city hall staff, etc. It was nice, but none of us could relax and everyone was afraid to drink much. We eventually changed and only invited our own staff and a few close people. The parties then became fun.
The “cold as hell” part is also the tendency to shut off our emotions because of all that we have to deal with on the job. Psychologists always tell us not to do it, but it’s difficult to avoid.
My best advise is to maybe to have get-togethers with just really small groups of people that he really trusts. No one at all that he isn’t 100% comfortable with. Maybe then he’ll feel like he can let his guard down.