Eternal Widow

Under an obsidian sky in a deep night, there lies a bright-lit city, suffocating the stars from vision. In this city a beautiful girl sat happy, in content, happy to be alive in such a seemingly wonderful place. The human perception betrays us far too much, as she should have been in ability to grasp, yet fails to. Still sat in that city, a man approached her with a smirk. After many a minute of small talk, the strange man claimed he could give the girl immortality upon one condition, she may only wed him. In haste the girl took the offer without further thought.
The wedding was planned and performed according to plan. The girl was gifted immortality. In her joy, she did not care to watch for cars as she crossed the street, she was hit hard, as if hit by a two ton bullet. Hospitalized. Her husband stayed with her for but an hour, than left her for another woman due to her injuries. At midnight that night, all her pain went away, all injuries just disappeared from her body.
Out of rage from his adultery, the girl killed the man and left his cold corpse to rot in the street. In death his soul was pleased, no more pain was connected to him, as his body was the only thing that retained his suffering.
From that day forth, every time the girl found love. She followed her urge to kill her mate, one hour after the first kiss. That girl will now live forever lonely and in pain. Although she resents the murders she commits, that urge always takes her body over, and widows her… Her heart shall hold nothing but pure dreadfulness for eternity.