Perfectly normal to have those thoughts when you feel a loved one is suffering or as an escape to the feelings of hopelessness their loved ones have.
Over the summer I watched my best friends young child waste away due to a rare cancer and I felt guilty about hoping she'd not make it through the night but that was because of the suffering her and her parents were enduring for too long. I felt guilty but my therapist assured me that is a normal response when we are having to go through very stressful or traumatic things.
Its your minds way of saying 'please make this stop'.