Hey ... the biggest mistake we women make is to think the guy can read our minds.
News flash .. they CAN'T.
If you are not feeling well and don't feel up to having sex, SAY SO.
Guys want sex. It is WHY they date women, and you will never find a man saying "Maybe we shouldn't have sex".
But a GOOD man can accept that you might feel sick and don't want sex.
No, you are not right to be annoyed.
You have your needs.
He has his needs.
And all relationships struggle when their two needs don't mesh.
Getting annoyed means you aren't getting your way, and you aren't working with your own emotional reactions. And people who do that are not ready or able to make a relationship work.
So you need to start learning how to take responsibility for the emotions that YOU create in yourself, and stop blaming others.
If you are still ill, of COURSE it is a good idea to postpone it.
And if he IS selfish then he will get upset and maybe even break up with you. But guess what .. if he is that selfish, then you don't really want him as a bf anyway.