My girlfriend is introverted and has been dating for a year. Now she is angry. She went to find her and avoided me if she didn't meet. She doesn't return phone calls or WeChat messages.

You may still be angry. You should insist on finding opportunities or explaining to her in the form of WeChat, and you must change your way of doing things next time. Communication is so convenient now. If you can't do what you promised because of temporary circumstances, you should call the other party in time. This avoids a lot of unnecessary anger.