Nick had a mixture of fear, guilt, and pity regarding Juliette's Hexenbiest. She had enormous power and was unpredictable so that's where the fear comes in. Juliettte became a Hexenbiest because of him being a Grimm and her relationship with him and it appeared to ruin her life so that's where the guilt comes in. In addition, he didn't have a high opinion of Hexenbiests at the time, they look like a corpse in their woged state, so that's where the pity comes in.
I don't think jealousy had anything to do with it. Nick never envied Juliette or wished he could do what she did. He never wished he could do anything that any wesen did. Not even Diana made him feel a sense of inferiority.
I don't think jealousy had anything to do with it. Nick never envied Juliette or wished he could do what she did. He never wished he could do anything that any wesen did. Not even Diana made him feel a sense of inferiority.