What are the rules on dual military couples?

You don't get 'stationed' in the Reserves. You stay in whatever unit you are assigned to unless you work a transfer to a different unit or have to move because you get promoted out of a position or your job goes away. So, if you are both Reservist at the same location, neither one of you has anything to worry about unless your job goes away or maybe if one of you makes E-8 or E-9.
The Join Spouse program is for active duty/active duty couples.
If you are active duty, then you can't be in the program. You will get assigned just like anyone else and she will either:
1. Follow you and commute to her drills
2. Follow you and try to find a job in a nearby Reserve unit
3. Not follow you.

reservist don't get stationed

if one is in active duty, married or not, the reservist still has to go to drill at their unit

girl friends mean nothing to the military

The joint spouse policy that all your active military services try to follow pertains to active duty married couples-not one where one of the spouses is in the Reserves. That being said your wife does have some options for remaining in the Reserves if you were to get transferred and I have seen these options exercised a number of times in situations like what you are asking about. Those options are as follows:
1. As a member of the active Reserves she can elect to go inactive and then she is in an administrative hold status where she does not participate for pay or points nor doing any drill weekends or annual tour. She can then come off that later and go back to active Reserve status once you get someplace that does offer her the opportunity to do that and then she enters that at her previous rank usually.
2. She can commute to her unit for drill weekends and annual tour. Her hotel and travel expenses might be picked up by the squadron and wing she is a member of depending on what her AFSC is. Some squadrons and wings have to do this for some to keep them and you especially find this with some of your flying units and those who hold flying slots for instance or those in medical squadrons like your doctors and nurses. Keeping them and paying for those expenses is cheaper than recruiting and training new individuals in those jobs and slots if they leave for reasons like this or other reasons and they don't live in the geographic area where their squadron is located.
3. She can try to go into the IMA program. That is a program where Reserve members report directly to an active duty unit and participate with them on a limited basis. Some of that participation is not for pay and instead for points and time towards retirement only.
4. She can also try to go into a Category B status. Right now she is in a category A status and this is somewhat like the IMA program. As a Category B Reservist she reports directly to an active duty unit and commander and participates for no pay on a limited basis while earning points and time towards retirement.
5. She might be able to transfer to another active Category A type squadron located near where you are reassigned to. There are a number of things that can impact her career wise somewhat especially if she ends up in an overage status but she would then be participating and assigned to that new squadron for pay and points and time towards retirement. There is a limitation on how long an individual can be kept in an overage status and participate for pay and points and that is usually a year with the possibility of a waiver and extension of a second year but beyond that then individuals usually have to then go with one of these other options if they want to remain in the Reserves.

I have seen these five options used by individuals in the Reserves to better fit situations like when they are married to an active duty member. Much of this also depends on the Reserve members AFSC, job experience, and rank also. As for deployments her deploying is totally independent of you deploying. She will have to have an approved family care plan in place for that reason once you have children in the event she deploys and you being active duty is not a viable excuse for not deploying even if you also are deployed at the same time or during some period of her activation and deployment.

There is no co location for reservists. You get assigned to a unit that needs someone with your skills.

Reservists don t get posted anywhere unless the reserves are activated. You just have a gf/bf relationship. The military can t be expected to take any notice of that.

If you are in two different services you are totally screwed. If you are both active duty in the USAF you can ask for a joint Spouse assignment. That is more likely if you are in totally different career fields, such as security Vs medical. If you are both in the same career field it becomes less likely because one of your will be senior and can not be in a supervisory position over the other. Bases tend to deploy as a unit so if they send a security unit they will also send some medical so you can try to arrange to go together. Great unless you have kids, then you have to figure out who is going to watch the kids while you both are gone. Do not plan on all your assignments being joint spouse, they could send one of you to Japan and the other to Germany. You will have to decide which is more important, your military careers or your marriage. You can not have both exactly the way you want. Both of you will NOT be able to do a 20 year career and be together those entire 20 years.

As a reservist, you live wherever you are, and never get posted, so, there are no issues at all. If you were regular force, being a married military couple certainly can be difficult. While they would try to post you together, there are no guarantees. But, as a reservist, this is not a worry.