Irving Andrade, 25, was out near Boulder Islands on Lake Mead with friends on Sunday when he went missing.
His fiance's brother, Luis Alvarez, decided to take a swim around 2:20 p.m. with his life jacket on when he says the currents got too strong. Irving jumped in to help, but he didn't have a life vest on and disappeared into the water.
Ariane Rivera, his fiance, just wants the loving father of two to be found alive.
"I can't give up; he's my other half. I can't give up," she said. "He would never have given up on me, I know that."
Ariane says she wants to remind everyone to wear a life jacket no matter what.
Rescue crews will make daily patrols for the next week to look for any clues. They are also looking for a 53-year-old man who jumped off a boat to go swimming and was seen going under water at Lake Mohave south of Willow Beach.