My ex-girlfriend who broke up for a month sent a message to wish me well on my birthday. I don't even remember it was my birthday. What does she think? Thank you for your help.

There are two possibilities. One is that she still has you in her heart and can't forget you. Take this opportunity to make up with you. The other is that women remember this date accurately. To be exact, you are still friends after breaking up. It is natural to bless you as a friend, so it depends on what you think. If you can't forget it, you can take this opportunity to make it up. If you really don't feel that way, don't care too much about your ex-girlfriend.