First of all, unless your boyfriend is a nurse or in the healthcare/medical field, DO NOT listen to him &/or let him control what you decide to do with your educational and career goals. He should be supporting you, not "brainwashing" you with excuses. On the other hand, to give him the benefit of the doubt, maybe he's insecure and worried that nursing school will bog you down, thus leaving less time to spend with him and on your relationship. That's partly true.....nursing school does ask alot of you(and one's family, if applicable) and can test your patience to the core. But you've got to do what's best for you FIRST and boyfriend second.
Secondly, I will not sugar-coat things: Nursing can be VERY stressful, mentally, physically, emotionally, etc,. However, alot of this depends on: what area you work in(LTC vs Acute Care vs Doctor's Office vs School Nursing, etc), the type of facility you work at(hospital vs nursing home, vs school, vs clinic/office), how many hours you work, your personality and how you view/handle stress, etc. There's so many things that factor into this. And Nursing school is no better or easier. There will be LOTS to read, study, know, etc. Lots of tests, papers to write, projects to do. Instructors will put pressure on you from left & right. At the end , most students, if not all, find it well worth the headache, stress, and time. On the flip-side, Nursing is also a VERY rewarding and fulfilling career. As a nurse, you are given an intimate and personal opportunity to be a part of a person's life. Maybe it's in labor & delivery, when you share in the start of a life by helping a woman through a tough labor on her 1st or 5th child. Or maybe it's in ER, Trauma, or ICU, when you care for someone close to death, yet able to pull through and make a full recovery. I could go on & on because there's so many positive and wonderful things about Nursing. That's one of the reasons why I love it and what I do.
Now, as far as working 80-90 hours, that's not something I can specifically say happens everywhere, or anywhere. At my hospital, it's a "common" issue, vs a constant one, to have employees working more than their "normal" hours, especially in the fall, winter, & spring months. However, it is not a requirement; nor is it allowed to get that out-of-hand that one nurse is putting in 80hrs/week. That's insane!! On the other hand, there are positive benefits for those who work extra, money being the most common. Plus, it can help out at yearly eval time becuase managers & co-workers take notice of those willing to be flexible with their schedules or work on a scheduled day off. Personally, I've picked up many extra shifts, switched shifts, and worked many, many, many hours of overtime as needed and available.
If you're still unsure about nursing & whether it's the right decision for you(and not because of the boyfriend), why not look into shadowing a nurse somewhere? Maybe even check into shadowing at a couple different places, facilities, or specialties, if possible. That way, you can get a firsthand, although not all-encompassing, idea of what "reality" nursing is all about and how "A Day in the Life of a Nurse" is spent. I'd also suggest that you do this before you start nursing school or get too deep in it.
Lastly, and more importantly, live your life the way you want to, and not the way your boyfriend sees fit!