Background
My partner and I have been dating for 9 years. We have been living together for the last 2 years. Since we started dating, my partner has not gone to the doctors for simple checkups, physicals, etc. Even when my partner is very ill and should go to the doctors they refuse.
I'm not sure the real reason for them avoiding the doctor. However they've stated a few times "I've made it this far in my life without a doctor, I don't need one till I'm really old"
I was only able to successfully get my partner to go to the doctors once, which ended in disaster as my partner refused most of the test. As a result the doctors couldn't give any information. To make matters worse the bill was very expensive and they felt even more resentment.
Problem
My partner keeps getting sick. Each time they get sick I also get sick. They have an "I'd die for you attitude" when I am sick, and think that I also have that attitude when they are sick. (I don't). Every time they get sick I ask if they'd like to go to the doctors or even bluntly tell them they need to go, they always refuse.
It's gotten to the point where they will hide their symptoms if possible to prevent me from avoiding them or telling them to go to the doctors.
Question
How can I approach my partner and discuss the benefits of going to the doctor. I want them to feel comfortable going, and I want them to know that the doctors can help. I also think I'll need to explain that the last time they went isn't a normal scenario at a doctors office.