There has been someone in the military in every generation of my family since the WWII. My oldest is in the Navy. He went in at 19. He found it difficult to assimlate to the strict rules of training. It's not like he can come home on the weekends or spring break like college students. He said it like being owned by someone. You have to remember that the military is making a solider. They reshape the way think, live and breathe for the most part. It can be difficult for free spirited people to submit to the type of brainwashing that the military does. My sister was in the Air Force and had a really difficult time in training. She was depressed and extremely unhappy. It is the most difficult thing in the world watching someone you love suffer, even more difficult to keep up the upbeat attitude so they can't see you cry. I can say this to you. My sister does not regret her term in the USAF. She said it made her a strong person. It was tough but she would do it all over again. My son is in Madrid Spain at the moment. He just left the Iraq. He is doing well. We email each other often. He calls whenever he can. His tour is up next June. While he says that the Navy has given him character and a strenght that he didn't know he had before. He has seen some of the most beautiful countries and he has met some quality people, he will not rejoin.
You need to keep up the positive attitude. Keep writing. Try not to talk too much about the happenings of her friends. (It will only make her more homesick) Encourage her friends and family to write also. Ask her questions about her training, the people she is meeting and some of struggles and triumphs that they are going thru too. No matter how bad the situation, there is always a bright spot somewhere. You can help her find it. She needs to keep telling herself that she can do this. She can survive this. She has no choice, so the only direction she can travel is forward.
You can find support for yourself by calling the local recruiting office. Ask if there are any groups you can join. It can help to be around others who have loved ones serving in the military. Thank her for me. It is a brave thing she is doing. I am proud of her and I thank her with all of my heart. My grandfather, father, 2 brothers, 1 sister, 1 son, 2 nephews all serve in the military. Keep the Faith and God Bless You.