Maybe he catches her off guard while she is swimming or something else as equally non-threatening. It would give him even more reason not to harm her. Perhaps another reason he is in the forest is because he was sent to find something or someone stolen and is after them. Maybe even Zarina's pet dragon, the dragons could have thought she stole him but instead he chose her. Which would explain the war, because small dragons are choosing to become guardians and companions and the bigger dragons think elves are stealing them?
That could be true. More worlds, we could have fun playing with that! I think the war beginning at that time would work perfectly. Maybe the first small dragon to leave is my girl's dragon because he senses sadness in her and wanted to comfort her? Thus starting the war.