I think poly really is a very valid approach to people who must by necessity spend long times apart.
Unfortunately I've seen WAY more cheating than poly in my 20 years of experience as a Navy wife. Some people have a DADT approach, some know it's happening, hate it, but ignore it. A lot of unhealthy nonmonogamy going on and it's unfortunate because there are other ways to go.
But I think that many people spend so much time away or prepping to go away, or trying to adjust to being back that it's hard to develop the relationship skills necessary to build a strong foundation like communication and skills in dealing with stress. I think often there's a real "boys club" when it comes to the military and deployments where they egg each other on to cheat on their spouses and then all agree to keep it shut. It's kind of the "what happens in vegas" theory, but on deployments.
I really don't mean to sound negative about it, but it has just been my limited brief experience. Hubs and I have talked about it a lot and I know a LOT of what he's seen because he tells me. Stress and alcohol and distance and dealing with people and god-forbid combat. Not a good combo.
As for playing it down, most people play it down in their work environments anyway, really. And the chances that the military here is going to prosecute cheating is SLIM to none. It's not really a valid threat around here...