My girlfriend sent me a short message sent to someone by mistake yesterday.

If your girlfriend sent you a message sent by mistake yesterday, you can consider the following measures:

1. Ask your girlfriend directly: You can directly ask your girlfriend what this short message is about and ask her if she sent it wrong. This will help you know more about the situation and avoid misunderstandings and unnecessary guesses.

2. Respect your girlfriend's privacy: If you think this message is your girlfriend's privacy, you can choose not to ask her and respect her privacy. However, if you think this matter may affect your relationship, you'd better talk to her.

3. Check the content of the information: Before deciding how to deal with this problem, you can look at the content of the information and see what it is. This will help you to better judge how to deal with this matter.

No matter which way you choose, the most important thing is to keep calm and communicate. This will make your relationship more healthy and stable.