My girlfriend won't return my messages. How do you gently express your anger?

Girlfriend doesn't return messages. Maybe it's because she's too busy at work. As a boyfriend, you should be considerate and understand her more. Usually you should know more about her hobbies and talk to him about what she likes. Or you can send a message saying, I know you are busy. Didn't see my message. Please send me a message when you are free. No matter how late it is, I will wait for you.