It is my belief that we co-create our lives right alongside of GOD - the CREATOR - our HIGHER BEING - (feel free to use whatever label that best aligns with your beliefs to name this power). In choosing to live out a physical life with a personality I feel that we pre-plan some of our earthly experiences, often joining up with other souls to experience life with. Our lessons come to us through our experiences with the people we live with, work with, and play with.
On a soul level a person better understands the gifts and insights they will learn in an earthly experience. Because of this they may pre-decide that the physical pain associated with an illness "is of less importance" than the soul growth that will come from it. Two souls who have contracted to experience the patient/caregiver role may have forgotten their pre-birth agreement. Forgetting our soul knowledge seems to be part of the package of taking on human form. These contracts may be so tightly woven that it is nearly impossible for us, in our human understanding, to recognize the gifts the patient who suffers pain is offering the caregiver and vice versa. The "caregiver" learns compassion and empathy for others in caring for the "patient." The "patient" learns what it feels like not to be in control and also learns how to accept help and caring from others.
Does the "patient" have to remain the "patient" throughout his/her remaining lifetime once the patient/caretaker role is set in motion?
Each circumstance is different, so I don't think an outright NO would be a responsible response on my part to this question. Our life lessons are interwoven so intricately that it would be impossible for any of us to make a concise evaluation about this. But, I think once the agreed upon lessons are learned or the original goals set are met, the experience itself can be LET GO of. The trick may be in understanding that our role-playing can end. We may get caught up in the game and become stuck in our roles. The "caregiver" can continue on by taking on new patients to care for if he/she chooses and the "patient" can become healed and direct their life experience along other pathways. Often times "patients" become "healers" after their lessons are learned. We take on a variety of dual-roles with other individuals throughout our lifetimes, these roles are ever-changing. Other dual roles that are often pre-birth contracted are child/parent, victim/abuser, wife/husband, employer/employee, student/teacher, etc.