I read some of this thread. I've dated a med student a long time. Actually, met her after she was rejected first cycle and was re-applying. She subsequently graduated and is close to done with residency and I got inspired and decided to go to med school.
Here are tips I would have given myself. First, I would have got engaged a long time ago. It never seemed like the right time. She was busy studying, a crazy intern, then residency and then I moved away. There is no right time with someone in medicine. Do your best and make things work once you know you are both committed to each other. Here is a year by year breakdown. You might be beyond first semester, but going to include it for good measure.
M1 year - First semester... let her be. She's probably not used to the med school workload. But, be sure to support her. A care package. Flowers. Chocolates. Cards. Anything to make her feel that you love and care for her, but understand she needs to adjust and need space to do this.
M1 year - Second semester - she will have gotten more used to school expectations and balance. You can get in a few date nights, but she'll be studying a lot. Care and support and you'll get in a few fun activities.
M1 summer - Honestly, enjoy this with her if you both have the ability to. My gf was huge into research and her M1 year fell into a time when I wasn't comfortable asking for time off (recession, people were being laid-off). In retrospect, I would have enjoyed this summer with a trip before/after her research. I didn't really know what was coming after this and nor did she.
M2 year - First semester is just a continuation of the M1 year second semester.
M2 year - Second semester. BOARDS! It's a reversion to M1 year first semester. Boards are a big deal. During dedicated study time (usually 6 wks leading up to boards), she won't exist.
M3 year - Depending on rotation, you may either see her a lot (psych/family) or not at all (surgery, ob/gyn).
M4 year - For most, this is where they likely will see their significant other the most. In my case it was quite the opposite. My SO, who was initially interested in peds, changed her mind and decided on a super competitive specialty. She decided to line up audition rotations in this super competitive specialty and even moved to another country for a while and was non-existent.
Intern year - I was not prepared and nor was she. Holy smokes! She went crazy. I mean... the stress. I was dating a crazy person. I questioned if we should even be together. I got yelled at and she was just completely not herself. I decided if I could deal with that, then I must really love her. I can't even explain what it's like being the SO of an intern (in a long hour specialty). Try and be supportive, but it'll be trying. If there was one point I thought it totally wasn't worth it, it was during intern year. She hated it, I hated it and we were both miserable.
PGY 2 - PGY 3 - These years were more chill. Still didn't see much of her, but she seemed to be enjoying medicine and the times we did see each other were really special. Lots of romantic restaurant nights and walks in the park when our schedules aligned.
PG 4 - PG5 - Added responsibility of being chief. More stress. But much more able to deal with it. Of course, this is where she springs on your that she wants to do a fellowship in another state and you're like... oh no, another move!
Just my personal experience. I think my two cents is love and support mean more than anything to someone in medicine. The ability to ask how they are doing, being there for them and genuinely caring go a long way. Know that they are just a ball of stress and anything you can do to be the person they want to call first to let loose will really help your relationship. Dating a person in medicine has its ups and downs. It has been worth it for me, but there is no way I would date someone else in medicine again if this relationship falls apart. Good luck!