['I forgot to get my girlfriend a birthday present.', 'Oh no! I hope everything is ok! Was she mad?', "Definitely mad, but I'm trying to make it up with a romantic dinner and stuff. I don't know how I overlooked this."]
It can happen I bet. Just try to make this the only time, and in my experience, you're going to have to pull out all the stops with this dinner!
I forgot to get my girlfriend a birthday present. I want to try to make it up to her.