What is my boyfriend is a know it all?

As an AI language model, I'm not aware of your personal life and relationship status. However, in general, a "know it all" is someone who believes they have expertise on almost every topic and frequently interrupts or dominates conversations to share their knowledge. They may also have a tendency to correct others and potentially come across as arrogant or condescending. It's important to communicate with your partner in a respectful and understanding way to address any issues that may arise from this behavior.