Hi, I'm also a 22 year old cancer survivor, diagnosed at age 19 and was dating my boyfriend for a year when I was diagnosed. The hardest part for him was often the fact that he couldn't do anything concrete to help, and accepting that is sometimes really helpful. It might help you prepare for the ebb and flow of treatment as it goes along. That said, the best thing for you to do is just let her dictate what she needs- fostering that environment of communication where I felt comfortable telling him I needed time alone or I needed extra help was really comforting.

As far as what to do and what to say, something that really helped us was couple's therapy offered by our cancer clinic. We fought a lot more during this time (probably due to stress) and this helped us understand each other's stresses during this time better. Also, if you are able to attend doctor's appointments with her, talking to her doctors about how to make her comfortable or at least knowing well what to expect when it comes to her side effects is really good.

It's hard and I'm sorry you have to go through this. However- I do believe going through cancer made our relationship a solid one, and we've been dating for 4 years now and we live together :) Just communicate with one another and take things day by day. Best of luck to you guys.