I'm going to lie about my boyfriend
What is your reason for wanting to lie about your boyfriend?
I don't want to tell people about our sick relationship. I hate him.
You don't have to share everything about your personal relationship but it is not good to lie to others. They will lose trust on you.
Fuck you, that's none of your business.
You do not have to share anything about your relationship that you do not want to. In addition to that however, it is wrong to lie about your partner. You are better off just not saying anything.