For the standpoint of view of the definition of living, it is, necessarily, for a living "thing" (as you said) to live alone. This is because if lived together with other "things", it would be the same with them. It must be said, we can not confuse the group livings, as sea corals etc, with a big living being. They are separate, for their living functions does not work in the same "body". For this sequence of thoughts, a living being simply cannot die "together" with other ones, simply because it logically cannot live "together" with them.
Yes, every living thing ultimately dies alone. Whether one dies physically alone or surrounded by friends and family, one always takes that final step into death on one's own. As sad as this may seem, it is the way of the universe and cannot be avoided. Everything ultimately dies alone.
My sister died alone, she did not tell anyone what she was feeling, even if there were people around that could hold her hand. I always ask myself, why didn't she call me. I always wonder, if she felt pain, or loneliness. I was told by the person who last saw and spoke to her that her last request was a towel and asked to be left alone to sleep on the floor. I think it is strange that she did not request to be with someone or speak to someone.
I believe that everyone is born alone and dies alone, despite how many people or things may surround you. When you are born you are born as you and yourself alone. It doesn't matter that your mother is right there, or the people helping her with the delivery. You are born alone as yourself. Even if you are a twin you are born as yourself, as an individual. This goes for death, too. You die as you and yourself alone. Even if theres someone next to you, you don't pass on as you and your mom, or you and your dad, or you and whoever you're thinking about. You die as you, and you die yourself as an individual human.
When your laying on your death bed, there's no one beside you to accompany you to the after life. You are born alone, you masturbate alone, and you will die alone regardless of what you really want to happen. The reality is that no one will be there to talk you into an afterlife of joy.
Living things dying alone may happen a lot in the animal kingdom, but for humans, we are usually with others surrounding us when we die. Unless there is some sort of accident. Animals usually purposely isolate themselves when they know they are about to die, but it seems like humans cling to others when the end of their life is near.
There are some circumstances that has caused a living being to die alone. Most of the time the one dying has friends, and family by their side. Some circumstances may be from a bad accident in which no one was around. Even in those cases a living being will die with a nurse or doctor by their side.
I think that there is no such thing as dieing alone. No matter what god is there even if you didn't believe in him. I guess you could emotionally die alone if you don't have anyone in your life to stand by you in you last minutes. Most people have some sort of family and friends or even like a pet they consider their family. In conclusion, someone or something will always be there for you.
No one dies alone. Even animals that die are surrounded by natural processes such as decay due to bacteria. Death is a lonely prospect. In human belief systems, there is an immortal soul that goes to heaven with other souls. In that spiritual respect, humans don't die alone because other souls are ready to help them in the afterlife.