I believe a person can die from a heart ache. I just lost a dear friend last week to an unknown cause. Her family. Two days later my friend's mom died. And she was a healthy woman. Rumor within the family was...that my friend and her mom was really close and that she couldn't take the stress of losing her daughter so she died from it. And on the flip side of that, I believe dogs can too. I raised 2 labs for years. They've had several liters together. One day I came home and found that the mom dog's leash had broke and she had jumped the fence - nevertheless, she was never found. Not a week had gone by that I began noticing changes in the dad dog .. He stopped eating and drinking water. All day you would literally cry out, loudly. One day I came home from work and found that he wrapped himself around the tree and hung himself. The crazy thing is that the 3 years I've had my dogs, the tree was never a problem because the tree was at the very very corner of the yard - in order for him to have gotten around that tree even once he would have had to literally kick and force himself in between the tree and the privacy fence. It was the saddest thing I had ever seen.
Believe it or not we had two guys that had worked together for decades at the same company. One of them died and the other on went to the service and just as he sat down and made his self comfortable and the service ended he also died....so I would say if someone misses someone bad enough or is use to being around the other they can actually die of heart ache....just as dogs have done the same thing for a long time they miss their litter mates and stop eating and drinking ...I personally think it is that they can no longer or want to go on and they go into a severe depressed state in which they are stressed beyond their bodies ability to handle and they have a heart attack they can not recover from...anyway that's my 2 cents