I was thinking and clannad and this popped up.
Hypothetical let us say you found the women/man of your dreams and you started going out for a while and are both madly in love and are about to marry.
However....
Before that could happen, they told you that they had some horrific disease(like nagisa...) And could be fatal and kill them any time.
They tell you they'd understand if you would want to break up and they'd be fine with it.
Let us leave the small details out about the hospital etc.
I think it would be pretty fucked up to leave her tbh however it would be more fucked up to have her die in 2 years?