I'm annoyed at my partner taking cocaine
Is your partner's cocaine use affecting you too?
Yes, I could feel it negatively affecting our relationship.
It's fine to be mad at someone for doing drugs. It's a reasonable reason to break up with them too.
Don't say that so casually, I don't want to break up just yet.
Well, if they don't quit the drugs, in the end you will either break up or do the drugs with them. Which is the better choice if they don't get help? Anger is a normal reaction to drugs done by a partner, so that part is understandable.