He's asking for advice
Nobody is saying to divorce his wife right this second, he should seek proof because the story and her actions are not adding up.
If he key logs and finds out she's cheating he's in a position of power, he will have piece of mind and can make a proper decision since she's never going to just come out and say she's cheated on him. Basically you're saying ignorance of the situation is better than finding out and laying all doubts to rest, and that is just dumb, especially for a man in the military. He clearly wants to believe she's never cheated, even though the picture he painted for us is pretty vivid.
Lies and deceit only make things worse? Yet his wife potentially cheating on him and possibly lying to him is just a moment. You're too pressed on going at "Coli nikkas this coli nikkas that" that you're just giving out shytty advice.
No being across the ocean maybe in combat knowing your wife is getting her back blown out will not grant you "piece of mind" nor will you really be able to make rational decisions.
And I never said her potential lying/cheating is a moment. I said committing your own lies and deceit to combat it is the wrong option.
I'm married, if I ever felt the need to stalk my wife I wouldn't be asking her "are you cheating"
I would be telling her. "I suspect your cheating and I'm probably gonna be checking on your communications"
Honesty and open communication is the way to go.