It's been a long time (Yandere demon x Reader)

He growled, both of his whole eyes turning pitch black, "Why do you care about this scum huh? Well it doesn't matter anyway, you are mine, and I'm going to show you who you belong to."

Y/n thought her world was perfect, she had the love of her life whom was her high school sweetheart. After graduation, he followed his fathers wishes and enlisted into the army. He never returned. Devastated, she locked herself away from the world. After two years, her family finally encouraged her to go out. She ended up meeting a real nice guy. But everything took a turn when her deceased boyfriend returned, but not the same as he previously was.