I'll say that this plays into "What are you willing to do and sacrifice for your love?"
From the looks of it, they're young and their relationship is still new as well. This is when problems arise when you begin to postulate the future and what you feel it should be. This relates to struggles and situations that will always arise during a relationship. The issue becomes, how much effort are you willing to put into maintaining the relationship?
My issue is, if she has this mindset off the bat with him being disgnosed with a life illness, rather than trying to put effort into maintaining that relationship, she would rather just throw it all away. If she did this, who is to say some other issue could've came up down the line, would she then put in effort to keep the relationship going?
She is willing to throw it all away, just because she has to face struggles and deal with these, make sacrifices such as not being able to do as what they both planned and saw their future being, life does not work that way and life brings tough times, life does not always go as you dream, this is the reality of life. So will you accept this change and try to make it work? Will you accept that life does not always turn out as imagined and that what you think the future will be is not set in stone, because reality and life just doesn't work how you want it to?
It shouldn't matter if you're married or not, having a connection and relationship with another human is caring for one another. Companionship in sickness is another one. This is how you show love, this is how you show one another you care.
Sometimes, it takes the face first smack into the wall of reality for people to realize and think about what they truly desire and want.