Apparently one of the two is married. So that would be considered inappropriate by most, particularly in such a public unit. But even in the Dutch Air Force, extramarital relationships within the service or with husbands/wives of fellow service-members, or affairs found-out by husbands/wives at home, may lead to transfers and/or being send back home during deployment.
Apart from the fact that it's frowned upon, affairs lead to stress and distraction with the people involved, meaning they are less capable to concentrate on their job, jeopardising their own and others' lives.
So the advise is: Don't get caught
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Mickey