Historias de Natuxlucy

One day, Natsu, Lucy and Happy finished a job. That same day, Happy catches Natsu and Lucy holding hands, so he teases them. Thats not it though, Gray ALSO sees them holding hands. Not so long after that, Natsu, secretly runs away. Gray, Lucy and Happy try to find Natsu, but they cant! Where did Natsu run off to, and why?