The couple first met at a coffee shop in Yishun when she was working as a beer promoter and he was a regular customer.
On Monday night, Ms Sim Yee Ling, 33, and her husband, Simon Tan, 42, were seen together for the last time at a coffee shop in the area with their two young children.
They were headed back to their Ang Mo Kio home after dinner when their Honda sedan skidded and crashed into a tree at about 1.15am. The accident occurred at the junction of Lentor Avenue towards Ang Mo Kio Avenue 6.
Ms Sim, a housewife, suffered head trauma and was pronounced dead at the scene. Tan, who was the driver, has been arrested for causing death by a rash act.
Ms Sim was born in Ipoh, Malaysia. She married Tan, a Singaporean, in January 2012 and later quit her job as a promoter to care for her two sons, aged three and six.
Neighbours told The Straits Times the family had moved into their three-room flat in Ang Mo Kio Avenue 10 about three years ago.
But the couple remained a familiar sight at the Yishun coffee shop where they had met, a customer told Chinese evening daily Lianhe Wanbao yesterday.
They frequented another coffee shop in the neighbourhood, where they had been eating dinner with friends that night.
Ms Sim was seated in the back of the car with her elder son, Tan Yu Sen, who suffered spinal injuries.
The younger boy, Wei Quan, sustained head injuries and was admitted to the intensive care unit at KK Women's and Children's Hospital. Both boys were believed to be in stable condition yesterday.
Tan, who suffered a brain haemorrhage, was in intensive care at Khoo Teck Puat Hospital.
Speaking at Ms Sim's wake in Sin Ming Drive yesterday, Tan's older brother said he had undergone surgery and his condition remains serious. "We have many concerns now. Who will look after the two children?" said Mr Tan, who declined to give his full name.
Neighbours described the boys as polite and well-behaved. Ms Sim was quiet, but would often invite other children to their flat, said a neighbour who wanted to be known only as Madam Ng.
The retiree said: "It's so quiet today without them around."
Neighbour Siti Nurulizzati, 13, said: "My cousins and I would go to their house almost every day to play."
It is not clear if the passengers were wearing seat belts when the accident happened.
Experts advised that infants and toddlers be buckled in car seats. Older children should use a booster seat. Singapore Safety Driving Centre training manager Gerard Pereira said: "All children should also be in the back seat. They are smaller in size and more vulnerable to the impact of an accident, regardless of the speed of the car."