Once my boyfriend and I join the Army (AD for him, USAR for me), what are the chances that we will get stationed together?

Here is how the Reserves work. When you join, you will be slotted in a unit that is going to be close to your home as possible (depending on the job you pick). The tricky part for you two, is that once he gets stationed somewhere, you are going to have to search high and low for a unit with your MOS that is as close to him as possible, contact that unit and see if they have an available slot with your MOS. Now, if a unit cannot be found nearest you, then what one of your options would be is to be willing to travel (driving or flying) as much as across the country to meet your Reserve Weekend obligations. And that is if he gets an assignment in the US first

I was married to another Navy Officer. When we were dating, no one cared about trying to get us orders close together. In the eyes of the service, "dating doesn't matter." Once we were married, they tried very hard to get us stationed together (which they did). Not sure how the guard does things, but I wouldn't imaging that it would be much different. The key we found, was talking to our detailers and making sure they were all on the same page. Get in touch early and often, rather than later. Give them time to work things out. Best of luck.

Your chances are about as good as Hillary Clinton ever becoming President of the United States. An easier COA would be for you (if you are prepared) get married, both join Active Duty, enroll in the Dual Military Program, then get stationed together. Once all the stars align for you the Army will send one of you on an unaccompanied 1year long deployment. HRC has a dark sense of humor.