At the Supernova music festival in Israel, scores of people were killed or taken hostage by Hamas militants.
Among those captured was Inbar Haiman.
Her boyfriend Noam Alon told Sky News he learnt she had been taken by “four terrorists to Gaza” through videos shared by local media.
“We know she was kidnapped and we really believe and pray for her to be strong and alive.
“We want her back here, to be safe, to be with us again,” he said.
“She is supposed to be here with us, she is a student, she is a smart, brilliant girl. They are citizens, they are not soldiers. They are not supposed to be part of this.
“She is the most amazing girl I have ever met, she is the love of my life.”
Numerous countries have said they are involved in negotiations to get hostages released, but Mr Alon said he had not been told about a specific plan.
“All we know is Israel is doing everything they can to return our loved ones back,” he said.