Never. Atleast not if it wasn't a necessity.

She'd kill him if he was truly in pain and there was no pain out, if it felt like a necessity to take him out of his misery she would. But not any other way would she ever take his life from her. His life is more essential then hers. She wants him to outlive her.

As for mental harm, if he was in the way of a "necessary movement". She would probably stop him. But not harm him physically, something probably like hypnosis or idkidk!