A Military SO is the girlfriend/boyfriend/wife/husband of an individual in any branch of any Military.
There is no higher civilian level of badassery.
To be a military SO (besides having a significant other in the military) you must:
-be able to survive a long distance relationship.
-be able to go for long periods of time without sexual intercourse.
-forgive any forgotten special dates.
-forgive lack of contact.
-have decent handwriting (for letters).
-have Skype (or any other video-chat service)
-have a charged phone on your person at all times (for unexpected calls or texts from your SO).
-be a badass.
Her boyfriend can crush you with no effort.