Kayla Mueller's Syrian boyfriend Omar Alkhani desperately wanted to save his girlfriend, even planning on lying to the Islamic State about their relationship status just to get her out. But Mueller refused to let Alkhani risk his life for her.

The Associated Press talked to Alkhani on Sunday and he revealed how he planned to pose as Mueller's husband after she was captured so that ISIS would consider letting her go.

But Mueller was convinced that he would be harmed, so she admitted they were not married.

"Since she's American, they would not let her go anyway. No sense to stay here, both of us," Alkhani said. "Maybe she wanted to save me. Maybe she didn't know I came back to save her."

When they were captured, Alkhani recalled how they would come up with ways to check whether the other was still alive, since ISIS prohibited them from seeing each other. He would cough or say something so she could hear his voice, and Mueller would cough in return so Alkhani was assured she was still alive.

When he was finally released, Alkhani was told to forget about Mueller and his camera equipment.

But he held out hope that they would be reunited again, even getting in touch with Mueller's family so they would know what happened to their daughter.

"I didn't realise one day I will receive this call from somebody telling me, 'I am sorry,'" he said.

There were also reports that surfaced stating that Mueller may have been offered as a militant's bride. When she died, the terror group sent photos of her body to her family in an e-mail to confirm her death, and one photo showed Mueller in a white burial shroud, which is considered a sign of dignity in the Muslim world.

ISIS said Jordanian air strikes claimed the life of Mueller.