I was talking to a girlfriend today who's had feelings for a guy and never told him until right before it was too late, giving her no time to develop any of their feelings for each other before he left. And neither did he. Both left feelings unsaid - she for fear that he didn't feel the same, him for fear of what changes the conversation would bring.
It's so easy to just think it and not say it. But you may severely regret not telling someone something. This wonderful lady and friend has some great things to say about this.