Some words are more than words. You must do what you say. If you can't do it, don't say ... What should you say to your girlfriend?

That means you let her down. You promised a lot of things, but you either forgot or just said it, but she was serious and looking forward to it. The higher people's expectations, the heavier the feeling of disappointment. So she is very sad and her heart is getting colder and colder. She is giving you a chance by reminding you. If you always let her down, she will leave you.