By your definition, that's Every guy who's ever been cheated on, not just the military. Being cheated on doesn't necessarily make you a cuck. Some females marry service members because they're attracted to the uniform. Some, attracted to the guy wearing it. Even still, others fall for the slick talk of some service members but they ALL have one thing in common, and that is, they have absolutely NO CLUE about military life as a spouse or girlfriend.
No matter how much a service member tells them about what they go through, the concept of working long hours, being separated for weeks and months at a time, constant excercises that can take you away, sometimes being unable to communicate long distance when you want, all of that is foreign to females. It's because they don't have to go through it and when they do, the Reality Check hits them hard and it's harder when a couple have children. In most spousal cheating incidents, it's due mainly from being away from home, either constantly or extensively. Those things don't make you a cuck, you simply got cheated on because females have this fantasy about military life going in and it doesn't change until they have to go through "the process". It's why the older NCOs are constantly in the ears of their troops when they get into relations with females about vetting them before marrying or shacking up. Being a dedicated and loving military spouse takes a special breed of woman (or guy for female service members). Being cheated on doesn't necessarily mean that a service member is weak but it Certainly means that the service member's partner is.