I went to the club last night with my best friend, his girlfriend and his girlfriends sister (not by blood so we're all almost exactly the same age).
The sister was married, so I was willing to dance with other girls because hey.. she's married, right?
NO! Last night, from 11pm to about 3am, we were at the club and she was grinding on me, doing stuff in the club that she should only have reserved for her husband. A couple times we'd split off and dance with other people, but we always got back together.
Towards the end of the night things got really intense.. but we didn't actually have sex. Now, I tell you all of that to tell you this. Her husband is a marine and he's oversea's right now in afghanistan (not for the army though, weird eh?) and he's coming back soon... Shoooooooould I be worried?
I mean, I'm training to fight and everything.. but that's a marine..
EDIT: And I said it before, but... HAPPY BIRTHDAY HIT!
Hmm your hand to hand combat training, against his rifle training.
Seriously, I wouldn't worry until there is something to worry about. If she doesn't say anything, then he will never know. There are some things that should be left unsaid. I would just make sure she keeps it quiet.
EDIT: Oh and it is easier for someone to be unfaithful when their significant other not around for an extended period of time.