Overview
You have reached a critical point with someone you care about -- you actually know how you feel, so today is the day you need to communicate it! This isn't about having too many expectations, either. You just need to share what you are thinking and what you are feeling. How the other person reacts is not something you can control, so it's not something you need to worry about. You will still feel vulnerable, there's no getting away from it. But you need to make them aware of your feelings.
