Cosmo but he is a Yandere for you

For Alastor simps

Kim (The woman in the picture) is an immortal human. She is 345 but forever looks 20. She had multiple relationships with different people but when all those people died she became extremely depressed but when she broke that was when she was with her wife Lunia, Lunia was a wonderful wife and person she died in her sleep at 35 and because of this Kim became completely emotionless, she was letter signed up for a nuclear war because of her immortality, she was the only woman who fought in the war and when all of humanity died because of the war Kim was the only one left. She just walked on Earth for the rest of the planet's existence