You are mixing a lot of things there Tom.
The VA is not the military medical system. There are two separate systems. The military system is the one that maintains the hospitals on the bases for the active duty and their dependents. It is funded by the Department of Defense and has some famous hospital in their system like Walter Reed, Brooks, etc.
The Veterans Administration hospital system is part of the Department of Veterans Affairs and is funded through that system. The people in the VA system are vets and not active duty. Often times the active duty will transfer their patients via a discharge from active duty to get them into the VA systems.
It is not clear exactly what system this former Marine is in. I am guessing that since her husband is still on active duty that she is likely using the DoD hospital via her dependent benefits and not the VA system. I could be wrong. But to get into the VA one usually has to show either a lack of other medical resources and honorable service or be service connected injured.