But let me give you a 3rd option. A middle ground between never dating and putting Ms. X through the pain of your illness.
That middle ground is this. Go date. Go have that relationship. It will probably end on it's own in a few months, as most relationships do. In case it doesn't end on it's own, you have the fallback plan of ending it if you get sick. Just slip into asshole mode, when you get sick, and if she doesn't end it, then you end it. Tell her you want to see other people, etc. That will hurt her, of course, but so what? If she wasn't dating you, she'd be dating somebody else, who, statistically speaking, would also end the relationship, and would also cause her that breakup pain that we all feel more times than we would like to. So she's not getting more pain, just the same pain everybody else gets.
Once you make up your mind that you will proceed on that course of action, you can go ahead and enter a relationship with no worries. Nine times out of ten, all this soul searching will have been for not, because most relationships end, and they all end painfully. On that 10th time, you have a plan to avoid inflicting any extra pain, by making it look just like the other nine times.
If they almost all end painfully, why get into relationships at all? Because it's worth it. In almost all cases, the area under the joy curve is greater than the area under the pain curve.