The model this comes from

Stroebe M, Schut H (1999). The dual process model of coping with bereavement: rationale and description. Death Studies, 23(3), 197 to 224 doi

A bereaved person moves between two kinds of activity. Loss oriented activity is facing the death itself. Restoration oriented activity is dealing with everything the death changed. Coping well is described as oscillating between the two rather than finishing one before starting the other, and getting stuck is described as avoiding one side entirely. The model was put forward as a description of how bereaved people cope, not as a treatment protocol.