Speaking as a current IP, I 100% agree with the other comments, you will not be able to go home every weekend to be with your fiance. No matter how much you think it is possible and how you will study on the airplane rides and so on, it will not happen. Furthermore, every IP I know does not allow their students leave while in training.
At this point you need to make a very tough decision, join the Guard or don't. If you do, given your desire to keep your fiance with her current job, I would recommend going through a court house marriage so she gets health coverage (though not 100% sure how the Guard treats family), and you get a small pay bump for being married. Then you go through UPT, see her when you can, which in reality will maybe be between phases (if you finish early enough) and on long weekends. Is it going to suck for about 2 years with UPT and follow on training? Absolutely. Have others done it? Absolutely. My wife and I went through essentially the same thing; Academy, then UPT, then more training before finally getting a chance to be together. If you have a strong enough relationship it will work out. But, if you're not willing to go through 1-2 years with minimal face time and contact then I'd recommend looking elsewhere for employment.