It is hard, especially when the SO relocates for you. They don't know anyone (usually) except maybe your friends and the SOs of your new vet school friends. And what a lot of people don't talk about, or care to admit, is that vet school changes you (or has the ability to change you). It is hard, it is taxing, and it is not always pleasant. It adds so much stress and pressure to you, that you turn into a stress-ball (or maybe an alcoholic...). You have to deal with the stress somehow. Some people party and drink, some people just become angry and anxious. The you that is in vet school is NOT the you that was pre-acceptance. And it is hard for your SO to process that unless they also went through professional school. I kinda feel bad for the SO as I used to be happy and laugh all the time. Now I'm grumpy. irritable, and always stressed out.
I think it is important to communicate with your SO your schedule and the amount of things you have to learn for the test. Some people have the SO help them study by quizzing them or whatnot so they can appreciate what you are trying to learn. For me, my SO would not be into that. I instead, just tell him when I'm going to be stressed and he should leave me alone. That doesn't always go over well...