Information, suggestions or topics on how to make a perfect love story.?

I'm trying to make a tragic,hopeless, unfortunate love story. i want it to be, somehow, a perfect one in which every part of the story is to die for. i created a well-fitted topic for it. it's mostly about a girl who was suffering from a non-contagious but deadly disease. she fells in love with a boy she met a few years ago, and that's how it all started. (I'm not asking a question but a suggestion)what would be the disorder the girl is suffering from??(please don't recommend leukemia, heart failure or some kind of a disease which includes paralyzing. it's very common.)thank you in advance for any helpful suggestions you may provide.