One thing I have learned, or really realized more over the past couple days, is that people can rely on certain events or dates to do the dirty work for them when they can't seem to muster the inner strength to do it for themselves. I know I was using Father's Day as a way to not really have to try to increase the intimacy or pursue W for ML. Because I KNEW that we almost always ML on Father's Day, I figured I could just wait until then and things would just "work out".
I think it's entirely possible that your W did the same thing with OM going away to basic training. It seems like she used this as a convienent stopping point rather than have to just summon the strength to do it 100% on her own, without special occasion. I DON'T think that's necessarily a bad thing.
I just hope for your sake and hers, that she now turns towards you and your marriage (oh, and all those unresolved issues she has) and you can build something of sufficent happiness and strenght that when OM comes a calling in 6 months, or a year from now, she'll be able to turn a blind eye and cold heart...towards HIM this time.
I KNOW you have put in the time and work. Now is the time to make all that pay off!