Officers only have the political department, and they can go out to study during their term of office, that is, they can study in schools, some training courses or other troops. If you are in a military region organ or a military sub-region organ, you may also go to the army to take a position. If you are in an ordinary army, you may also go to other troops for business, study and even exchange. It is also possible for troops to go to other places for training, perform urgent tasks, and even go abroad for peacekeeping. From your description, the only doubt is that you have to go back to the army every few months. If you don't study for a long time, it's really hard to understand during the winter and summer vacations. Generally, you can only go back to the army when you go out to study. But from your description, I guess you can't figure out whether he is going out to replace him, waiting for a position, staying in training, studying or performing a task, right? It's just that he may be studying this time, so you regard all his previous business trips as studying, right?
You can go to him if you don't trust. No matter where you study, your girlfriend can go to see him, and cadres can stay, usually for no more than 7 days.
Downstairs is entirely local speculation. There are a certain number of places every year, not all cadres will, and the replacement time is usually half a year, not one year. The difference in rank is only the difference in treatment, not the difference in opportunity. It is by no means the patent of senior officials.
Soldiers have military specialties and may also go out to study, such as driving cars, driving machine parts and training dogs. And they can also enter the NCO school. Some of them study abroad for two or three years. Going out to study has nothing to do with getting married or not, but only with the needs of the army.