I'll try to expand on what others have said and try to put some numbers on things.
Assuming that you are 21 years old right now and are a Sophomore in undergrad...
Step 1: You have two more years of pre-med/time prior to starting medical school. People's experiences range widely. Some people don't study very much, take the MCAT, enjoy the time before medical school and then start. Some people live in the library and spend 60-80 hrs/week either in class or studying. The vast majority fall somewhere in between. Only you know how you will spend these remaining two years preparing for medical school compared to other careers. Will it be 10 hours a week? 20 hours a week? 50 hours a week? 80 hours a week? It is very difficult to have hobbies, socialize, romantic relationships etc. working 80+ hours a week. You can have some, but certainly can not have it all. The time after interviewing and before starting medical school is relatively free time ~6-8 months. Little pressure to work your ass off, but it is limited, finite.
Step 2: Pre-clinical years. The dirty little (not so well kept) secret of pre-med is that no matter what you do prior to medical school, everyone starts on the same page on day one. Some people are better prepared to take on medical school, but content wise, virtually everyone starts on the same page. The range is wide. In terms of time spent studying/in class/in school, I'd say the range is 15-80 hours per week. How much time YOU spend studying depends on two big factors. #1 How good of a student you are. #2 What your goals are. If you are the kind of person that needs to be near the top of your class, but needs to work extra hard compared to those students that 'just get it' or have an eidetic memory, be prepared to give up a considerable amount of time. Remember, by the time you finish your pre-clinical years, you will be 25 years old. Depending on what state you live in and your gender, half the people in your demographic will already be married (~10/50 states for women).
Step 3: Clinical years. 50-90 hours per week is standard at most medical schools. Depends on what rotation you are on and what site you are at more than who you are as an individual. Yes, you can cut corners. Yes, you can bugger off early, but your clinical grades will suffer considerably and will be hurt in the match. While you aren't 'working', your schedule functions like that of a job. People are pretty understanding of medical students needing personal time or upkeep on their relationships, but you can not expect to be out early to pick kids up from school. You can't expect to make dinner every night. You can't expect to be able to have the free time for everything.
Step 4: Residency. 3 to 9 years. 60-100 hours per week. Yes, you are capped (for the most part) to 80 hours a week. But, those are limits on your clinical duties. Gotta do presentations, studying for boards/inservice exams, research, etc as well. By the time you START residency, you will be 27. In all but the Northeast, if you are a woman, more than half of your demographic will be married. (44/50 states) You know all that drama on medical TV shows? Yes, it is fake, bs, total garbage 90% of the time. But, that 10% that happens because doctors put their patients first? That is real. Sometimes you can't leave. Okay, you can. But, a patient suffers as a result. You should not be going into medicine if this isn't okay with you. You should want to stay. Maybe want to figure out a way so that it doesn't happen in the future. But, you gotta be willing to stay.
Step 5: Real doctor! Okay, so now you are somewhere between 30 and 36 years old. If you are the average person, you have never worked less than 50 hours per week and most of the time have been working 70+ hours per week. Now, you have to join a practice, private or academic, you are still the junior most partner. You have to prove that you belong. You have to bring in the cash flow or teach or whatever it is that you want to do. In surgery, that means a lot of call. That means working HARDER and LONGER than as a resident. In other specialties, maybe not so much, but it isn't exactly a cake walk.
I'm an optimist. Honestly, I'm the happiest person that I know. I am married and have been with my wife for 10 years now. We do not have kids or plan to have them. You can be a doctor and be happily married, have a family, etc etc. But, it is harder. Anyone that tells you differently is either trolling you or delusional. If having a family and a family life is the end all be all, medicine is going to make life difficult over the next decade plus. Is it possible? Yes. Does it mean sacrificing other things? Absolutely. A lot of it comes down to what your spouse is doing both in terms of career and family.