You want to tell him - everything
You might have great conversations with someone you're merely dating, but when you find yourself in love territory, you usually want to share everything with the person you're with. Whenever something happens during the day (from getting kudos from your boss in a meeting to tripping on the sidewalk on the way back from lunch), you want to tell him about it. Whether you text him about the fall or send him an excited email about how much your boss loved your presentation, falling in love means wanting your man to know what's going on in your life as a way of bringing the two of you even closer. While you may not feel the need to tell some guy you're dating that you finally managed to teach your Jack Russell to roll over, this is something you will feel the need to tell the person you're in love with.