When a patient won't accept help from family/support system

I'm just a nursing student at this point (just got accepted into nursing school so no experience). I had a recent situation with two elderly family members that got me thinking about about how to delicately balance a person's emotional needs and trying to handle a medical crisis. In this case the family member is in her 80's and a bit senile. She had lost her appetite due to antibiotics after a minor skin surgery. Her husband, also in his 80's, would not push her to eat and drink, and so she lost a good amount of weight. 22 pounds in 21 days to be exact. She was not a big person to begin with. He waited for the followup surgeon's appt, assuming that the surgeon would address all her medical needs. The surgeon addressed the weight loss by recommending that she see her GP as soon as possible. The husband did not understand why a GP was needed, and did not make the appt, thinking still that the surgeon would handle all her needs. If the surgeon did not put her in the hospital, then he assumed she was still okay. I explained to him that the surgeon would only address the skin wound, and the GP would address her lack of appetite and weight loss. We all encouraged him strongly to take her to the ER or to the GP without delay. All attempts and offers for family to come there and help them (they are out of state but we have enough people willing and able to drive there to help) were refused with anger. The husband has become more combative and stubborn in his old age. He was not able to see the reason of taking her to the GP or ER. Nor could we speak to the GP ourselves about our concerns as we didn't know who he/she was, and it would probably violate some kind of privacy laws. The family argued over whether to respect their rights to choose their own actions vs. intervening and seeking medical care for the woman. Finally the husband himself saw that she was getting lethargic and took her to ER. She was very dehydrated and emaciated but is making a recovery now in the hospital.

The crisis is over, but it got me thinking-- you need to respect adults to make their own decisions but clearly when their decisions are not safe, at what point can someone step in and insist they seek medical help? I understand that sometimes the courts can award guardianship over people-- but that's not what our family wants at this time. When we tried to be advocates for them (offering to drive there and go to the doctor with them) they angrily refused our offer to the point that the woman's health was seriously compromised.

As health care professionals, how do you deal with this situation? I felt like my relative was slipping through the cracks through misunderstandings about the medical system, and age related mental states.