SANTA ANA, Calif. -- The family of a California woman missing for more than two months is offering a $5,000 reward for information that leads to her whereabouts, according to police.

Erica Alonso, 27, vanished after going on a Valentine's Day date at the a Costa Mesa lounge, family tells 48 Hours' Crimesider.

Alonso and her on-again, off-again boyfriend, 45, were reportedly offered a ride by a couple from the Sutra Lounge, southeast of Los Angeles, to his home in neighboring Irvine in the early morning hours of Feb. 15, according to CBS LA.

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The couple reportedly left around 3:45 a.m. About 15 minutes later, the boyfriend told police Alonso and he got in a fight, and she stormed off.

Her white 2014 Honda Civic was found in nearby Aliso Viejo, about one mile from her Laguna Hills home, late last month. Neighbors told CBS LA the car had been parked in the area for some time.

"We are hopeful that somebody out there knows something, and we're hoping that someone's going to come forward," Alonso's brother, Isaac, told 48 Hours' Crimesider. "We feel anybody coming forward could be the one to break this case open."

Isaac Alonso said that his sister's boyfriend wasn't close with her family, but that the two were trying to work out their on-again, off-again relationship before she vanished.

Right now, detectives don't have anything to indicate a crime has been committed, Lt. Jeff Hallock, an Orange County Sheriff's Department spokesman, told Crimesider. Alonso's boyfriend has been questioned by investigators, and he's cooperated with police, he said.

"We believe he's the last person who saw her, so obviously that causes us to to focus some attention on him," Hallock said.

The boyfriend isn't a suspect and the information he's provided has checked out, Hallock said.

The couple who offered them a ride reportedly contacted authorities after seeing news reports with Alonso's picture.

"We never want to fear the worst," Isaac Alonso said. "We just want her home safe."

Anyone with more information as to Alonso's whereabouts was asked to call the Orange County Sheriff's Department at (714) 647-7055 or (714) 647-7000.