Why is adultery a crime in the military?

Because adultery is counterproductive to loyalty, duty, respect, selfless service, honor, integrity, and personal courage and it jeopardizes the ability to focus on the mission.

1. Goes against Good Order and Discipline.
2. Morally Wrong. If you breach this Moral Compass what else are you breaching?
3. Working in the Intelligence Field it makes you an easy target for Blackmail.
4. You sure as hell likely to be involved in a Divorce Situation, that takes Money and increases the liklihood of you being recruited to spy against your own country for Money.
5. Lots of states still have on the books laws against "Removal of Affection" which are very rarely applied but can be.

Original Military Law was built around the original laws of the land which were based on the 10 Commandments. The laws we have today are all still traced back to the 10 Commandments but have had to be more specific because, don't take this wrong, people tend to "bend" rules to their liking. Adultery is Adultery whether it is with a civilian, fellow service member, or service members spouse.

It's a matter of trust if you can't keep a vow to your loved one or respect the vow someone else made, it makes it harder to be trusted. If you apply that to say a sensitive position in which you have need of a security clearance to conduct your job it may be exploited by enemies of the country that find someone who is cheating.

In the military, we are supposed to be above reproach. Just because civilians are doing it doesn't make it right. Marriage is (or at least supposed to be) a vow. I'm not quite sure how it works with swingers, though, since technically it still is adultery. Just because people are out there in Colorado and other places smoking pot does not mean we are allowed to. It stinks, but we also raised our right hand and swore to abide by the UCMJ. In essence, it is breaking multiple vows as well as possibly diminishing unit cohesion, depending on who the cheater, cheated on and/or fling is.

Why do you want to hear more than an "Army" answer but your question is asking why it's a crime in the Military/Army? Im so confused.
Anything to do with a Soldier on anything is going to be an Army answer. The short answer to your question is because this is the Army not Texas A&M (insert any other college here).

Its not just in the military:

http://www.wral.com/nc-one-of-seven-states-that-makes-cheaters-pay/13599861/

I'm going to kill two birds with one stone, and cause some butt hurt while doing it. Both sodomy and adultry are illegal in the military because the military doesn't want SMs to have fun, lmao.

I know adultry should not be played around with, but on a more professional and personal level, it just takes away from the ability to trust people. In my Blue Book from Basic, and yes I still have it and revisit it from time to time.

Trust is the first thing someone must have for you in order to follow you and your orders. If someone is known to cheat on their spouse, or sleep with other peoples spouses you begin to question what other things that person does. I don't have the most agreeable moral/ethical compass but even I would find it difficult to trust someone that is known to "creep around".

I would say it is because we hold ourselves to a higher standard than civilians. Adultery is a pretty clear violation of our corps values of honor.

SFC Thomas,

Here's my opinion of it and maybe it's what you consider to be more than an "army" answer. For some people, adultery committed between SM to SM is definitely frowned upon. Causing disruption within the ranks, discontent, animosity and quite possibly violent reactions that will totally take away from the unit's mission because the command must focus on rectifying the situation once it's out. However, SM to civilian is not so much in the light and to some not as bad. But, I pose this question to you. Being that we are the defenders of freedom and protectors of the people, how can we hold ourselves to that title if something we're doing in private is ultimately hurting those we're commissioned to protect?

Yes, they family that we're destroying may be civilian but aren't we the ones who are supposed to make them feel safe and sleep at night? We can't do that if our extramarital sexual exploits are affecting them in such a high magnitude. Also, how would it feel if that SM who committed adultery with a civilian was married to another SM? And what if that SM was you being cheated on?

Some may think that it's not a big deal because the nature of the act is SM on civilian but what they don't realize is that personal lives do spill over into our professional lives. Even if the negative side effects didn't accompany the act, how could you trust someone you'll only see a few years to have your best interests if they cannot even honor a vow they made to someone they opted to spend the rest of their life with. Those core values are there for a reason and should mean something to all not only in their military life but their civilian life as well. Just my opinion.