Describe the Time Traveller’s new friend. Why does the Time Traveller believe she becomes anxious when he is going to leave?

On his third day, the TT saves a young female creature from drowning in the shallow river. Later, she presents him with a garland of flowers. Her name is Weena, and the TT explains it was the beginning of a "queer friendship which lasted a week, and which ended--as I will tell you!" Weena follows him around like a puppy, and she is distressed when she cannot keep up with his explorations and is left behind. The TT explains that he did not know until it was too late what he had "inflicted upon her" each time he left her behind, nor did he understand what she meant to him. He learns that her only fear is of the dark, and that after dark, the creatures sleep only inside in groups. Still, the TT continues to sleep away from the groups. Weena eventually sleeps next to the TT.