A Bronx woman was viciously stabbed to death inside her car while her boyfriend apparently relieved himself on the side of a desolate road Wednesday night — but her family thinks there may be more to the story.

Anthonella Contreras Linarez, 30, and her 44-year-old beau were on their way to dinner on City Island around 8:10 p.m. when the couple pulled over just outside Rodman’s Neck — allegedly because the husband had to urinate, law enforcement sources said.

Her boyfriend told cops two men pulled up on a moped while he was doing his business, tried to rob Contreras Linarez and stabbed her multiple times when she resisted before fleeing.

Her significant other told police that he rushed back to the car and tried to stop the thugs, only to be slashed while trying to play hero, sources said — a story the victim’s family is struggling with.

“The only question I have for him is, what happened?” the slain woman’s brother, Mayker Contreras, told The Post Thursday.

“We’d like to know what happened. We want the truth of what happened,” he said. “I’ll tell you the truth, I don’t trust what he says.”

Sources said Contreras Linarez and her beau of three years were on their way to meet a friend on City Island when the horror unfolded — leaving her mortally wounded with multiple stab injuries to her face, neck and body, sources said.

The injured boyfriend said he got back behind the wheel and drove to Montefiore Hospital in New Rochelle, where Contreras Linarez succumbed to her injuries, cops and sources said.

Her boyfriend was listed in stable condition and has since been released from the hospital — and is now being questioned by cops.

“Devastated,” Contreras Linarez’s heartbroken dad, Marcos Contreras, said of the incident. “Police are investigating, so I can’t say it wasn’t that way. I have to wait until the police investigate.

“There is always doubt,” the grieving father added.

The family is originally from the Dominican Republic, and has been in New York for about 11 years, they said.

Photos released by the family show Contreras Linares celebrating her graduation from Manhattanville College in Westchester County, and her boyfriend widely smiling in a separate photo.

Now, Mayker Contreras said his sister’s death has destroyed the tight-knit family — and left them questioning her death.

“Why, if you were with her, how did you let this happen?” he said. “Because if you have a wife or a daughter, and if your wife is in danger, you give your life for your wife.

“We’re devastated,” he added. “The light of your happiness — everything that has represented joy in your family, in your home — it’s gone. The glue that kept us together it was her.”

The alleged moped-riding suspects fled the scene after the attack and had not been caught by Thursday, cops said.