After Tohru watches Kyo get angry and refuse a girl's confession to having a crush on him, she discovers that she is afraid he will push her away like that one day. As she thinks this, Kyo is walking in front of her, and she reaches out, not knowing what his reaction will be. His response is a heart warming smile as he grabs her outreached hand.
This scene really showed how Kyo has grown, and how much he cares for Tohru. It also shows Tohru's true fear, of being left behind, and she allows herself to just be, especially around Kyo.
What Tohru doesn't realize in this scene, but everyone else notices, is that she is the exception, not the rule.