I'm going to break off my friends relationship
What makes you want to break things off?
She has a real inferiority complex to my girlfriend. I think she is an immature person.
You should not do things that interfere in others' relationships. You should respect the relationships that your friends have so they will do the same for you.
Don't talk to me like that! I'm going to break off this girl's relationship even if it ends with her hating me.
I think that is what is going to happen if you keep up with the interference. It is not okay to do something to effect the relationship of someone else. It is none of your business.