I applaud this part and I was going to say something similar but then I realized I don’t have the context of your relationship. Residency, IMHO, is the hardest portion of the life we chose.
So yes, be supportive...if you plan to follow where she goes, then mean it. But don’t tell her you’re willing to, if you’re not.
If you’re both from San Diego, CA and she really wants to do dermatology but only gets one interview in Detroit, don’t get too excited that she matched at her backup in Internal Medicine in SoCal. What sounds like a victory to you could be crushing for her.
So I guess what I’m saying is...use this forum to educate yourself about the process and what is in her control and what isn’t, so that you don’t become another variable. It may sound callous but we’re offering to help you understand in some small way what she’s going through.