I hope my friend asks out his crush and gets rejected.
I'm sorry, why would you hope for that?
I think they are a weak couple and they will break up on their own.
I think it is wrong to hope that bad things will happen to your friend. If they break up then so what, they will learn from it. I think it is best to just stay out of things and support your friend instead.
Don't they hope that their friend gets rejected?
No, I don't. I really think you need to review how you think of others, you need to treat them better.