Final answer:
The patient indicating regret and unfulfilled life goals is showing signs of the depression stage in the Kübler-Ross model of grief.
Step-by-step explanation:
The patient expressing regret for not taking better care of themselves and feeling that they won’t be able to accomplish what they wanted in life is exhibiting signs of the depression stage of grief. According to Elisabeth Kübler-Ross's model, the stages of grief are denial, anger, bargaining, depression, and acceptance. The Kübler-Ross model explains that these stages do not necessarily occur in order and that not everyone experiences every stage. However, the feelings of regret and hopelessness described by the patient are typically associated with the fourth stage, depression, where the individual starts to recognize the inevitability of death and feels an immense sense of loss.