Nurse or Girlfriend??

Saw two couples today in two different restaurants. Each couple included a man in his late 70s or early 80s and a Thai woman about 30 years old. The man in both cases was basically an invalid, I have seen couples like these before, I have never been quite sure if the girl in this relationship was a girlfriend or nursemaid. Maybe she is a combination of both, maybe she nurses him and also provides a trusting relationship as well as a sexual one at times.