I expect my SO to be compassionate and nurturing towards me while I'm sick, even if I'm mean to them.
Why is it okay for you to be mean to them, but you expect them to be nice to you?
Because I'm sick and I'll feel even worse if they're mean to me.
Of course you want other people to show you kindness, but you really need to start by being kind to everyone else. It's unrealistic to expect others to treat you better than you treat them. Even if you are sick, you need to be nice and not just demand that other people take care of you.
I just want someone to take care of me.
Even more so, if you treat your SO nicely, they will want to treat you with care and love back. You'll not only make them happier but you will feel a sense of mutual empathy as well.