The other thing, which is probably more important is just making the transition from being a preclinical student. Given the things you've said about how this is affecting your life outside of the hospital, I think you need to recognize (as well as have your loved ones recognize), that there's been a fundamental shift.
Whereas before, you had a great deal of freedom and control over your time, this is no longer the case. Before you could cut out of a lecture early, decide to study at home or the library or the coffee shop, you could study for 30 minutes or 12 hours depending on what you had going on that day, and while you might have felt guilty about missing a chance to go over notes one more time, in the end it wasn't a big deal.
Now, as a third year student, you have to be where they tell you to be, when they tell you to be there. You can't just cut out early and you'll have a few overnight calls, and even if the residents are wasting your time, there's little you can do about it. You'll figure out quickly that it's difficult to commit to important events because you find out about them either too early (and have no idea what your rotation will be like), or too late (and thus know you're committed to being on call or giving a presentation or whatever). And while the studying of third year is much less stressful and time consuming, you'll likely feel like now you absolutely zero free time.
This can be a hard transition, one that some people continue to struggle with well into their residency (the being on time and on location aspect only gets worse). And to some extent, friends and family came make the transition a really easy one or an impossible one. But the sooner you come to grips with it, the sooner you find little ways to make time for friends and family, and the sooner you realize that your not choosing your career over loved ones, then the sooner your stress level will diminish.
These are the sacrifices you have to make for your patients, and unfortunately, your youth is the victim. There's no way around it. Every resident, fellow and attending has multiple stories about the things they couldn't do, or the way they let down this loved one or that friend because they were at the hospital or clinic.
That's not to be a downer, just reality. In return for these sacrifices and hard work, we get all the rewards that the pre-meds on this board dream about. And we get to do work that's far more meaningful and important than practically any other profession. But it comes down to attitude, accepting the sacrifices and making it over that mental hump.
