A man stabbed his wife to death in a jealous rage Saturday outside a relative’s Bronx home, where the couple had tried to smooth over their rocky marriage, witnesses and police sources said.

Wife Amarita Khan, 25, had just left the house and walked onto Hone Avenue at around 6 p.m. when her husband Nazir Khan came out behind her and plunged a gravity knife into her chest in front of some 30 horrified onlookers, cops said.

The accused killer’s mom, Nafeeza Khan, couldn’t believe her son could have done this, saying: “He love her so much.”

Speaking at the couple’s home in Jamaica, Queens, Nafeeza said Nazir caught his wife cheating.

“My son catch her, she and the other guy,” she told The Post. “He see everything.”

Nazir works as a fuel supervisor for an airline based at LaGuardia Airport, a source said.

He suffers from a bi-polar disorder and was treated at New York Presbyterian Hospital for that condition in October, his mom said.

“I was shocked. I never think he is capable of this. He’s a quiet boy, a good boy. No smoking, no drinking, always just working,” Nafeeza said.

“I never expected my son would do something like this. He a very quiet boy, very keep to himself. Never tell nobody nothing, just `Good morning and good afternoon.’ ”

Witnesses near the Bronx slaying had attended a party being held on the block.

“We heard screaming, but we thought it was the kids playing,” said resident Melissa Ovando. “Nothing like that ever happens here.”

He stabbed her multiple times, cops said.

The Queens couple has two daughters, 2 and 5.

They had a huge argument Tuesday night, when Amarita took the kids and they spent the night at a relative’s home.

“It’s terrible right now,” Nafeeza said. “This [marital strife] was going on for a long time.”

Nazir and Amarita were visiting relatives to talk through their marital difficulties when the husband lost his cool and took the knife to his wife, cops said.

For now, the kids are staying with Amarita’s parents but Nafeeza hopes to see them soon. “I want them,” Nafeeza said. “I want to mind them.”