I was a Drill Sergeant and a Platoon Sergeant, served in the Army for 17+ years. I will tell you that around 50% of the females who joined were trying to get out of a relationship and thought the military was the "easy" way to get out. The others were either looking for college money, or legitimately wanted to serve.
Your girlfriend, no matter what the reason, will be doing something that will improve her self-esteem, confidence, and independence. She will have very little in common with the girl you knew after her Basic and AIT training is done. The hard fact is this- she will have had a multitude of new experiences that you can not begin to relate with. The biggest problem for people dating new recruits is that nothing changes for them, but the person who joined is now completely different, and sees them as not doing anything with their lives - honestly more women than men feel this way.
Drill Sergeants are trained to build up recruits confidence and self reliance and I saw a large percentage of females dump their boyfriends after Basic Training. Some who kept their boyfriends then dumped them after AIT. Most gave the reason that they were going to be stationed at "X" Base, and lower enlisted are required to live on post in barracks. That would mean she could only see you when she has leave, around 30 days per year. So unless you are planning to move to live near her, and then see her when she is not on duty (12-16 hour days are not uncommon), deployed, or in "the box" training for 15-30 days in the field, depending on her MOS you will hardly ever see her.
