In qualitative methods you are going in without any preconceived ideas of the person's reaction to an experience or event. In your case you are assuming care taking of an HIV person is a burden and requires coping on the part of the caregiver. In a true qualitative study, you would not make those assumptions. You would need to go broader and only assume the caregiver would have an emotional reaction to care giving. Phenomenological interviewing is good because you can ask about the experience of care giving without any direction implied. I don't know for example parents taking care of children with HIV would classify their care giving as a burden.