Arin Sur of the planet Ungara was the sister of the legendary Green Lantern Abin Sur and the late wife of the renegade Green Lantern Sinestro. They had a child together, who they were forced to give up for adoption, named Soranik Natu, who would eventually become a Green Lantern in her own right. While they were still together, Sinestro had made the decision to impose his will on his home planet of Korugar. He felt that because they had been in a civil war for decade, his decision and will was the correct way for the planet. This didn't go well.There was opposition to Sinestro's rule. In an attack against him, the destruction is what caused the death of Arin. Because Sinestro did not think of the consequences of his actions, it resulted in the death of the only person he cared about.
Major Story Arcs
For more information see: Blackest Night: Green Lantern
During Blackest Night, Arin Sur was resurrected with her brother as Black Lanterns and attacked Sinestro and Hal Jordan. She was destroyed by their combined light.
Sinestro: The Demon Within
For more information see: Sinestro: The Demon Within
Arin Sur is seen in a flashback of Sinestro's life before the Sinestro Corp.