If you don't get married and live alone when you get old, I wouldn't necessarily choose euthanasia because not getting married and living alone are two different concepts, if you don't get married you don't have a partner, in fact if you do get married, you may die alone because your partner won't necessarily die on the same day as you.
But if it is a lonely life, because not married he can adopt a child, or he can always fall in love, or with their own relatives and friends or some of their own business. All these are acceptable. But no one is born with a preference for loneliness, they all have their own reasons. So I don't think I would choose euthanasia if I were to be alone in my old age. Because sometimes when you get old, you have more thoughts. To put it bluntly, in old age, if you are still lonely, you may not be able to hold out, will be euthanized on the day of the road of suicide.
My mountain village, there was a disabled person, he had a neighbor, they live in a place where there is not much people, the two are male, are not married, to the old, have been dependent on each other, and then one day, the disabled person first died, the neighbor did not make a sound at first, we all think that is the old man, should be able to see the open, and did not think about it until one day, the old man was found dead, and then the old man was found dead. One day, the old man was found dead in front of the disabled man's grave. On the graveyard there was wine, chicken bones, and some leftover plates, and a bottle of pesticide ......
So I think if I don't get married and die alone, I won't be able to hold out until the day I choose to euthanize myself maybe, when I'm 50 years old, I don't want to live anymore because I can't stand the loneliness.