Many have suspected it for years, but now research has proved that driving with your other half sends your stress levels soaring.
Motorists feel four times more anxious if their partner is alongside them in the car, according to a study.
Researchers at Allianz Insurance said: 'Drivers are happier, more confident and focused when driving by themselves.'
As well as quadrupling stress, 'partner pressure' was found to make motorists feel twice as rushed, increasing the risk of them having an accident.
Drivers told pollsters that the addition of any passenger increased their stress levels but that they were least relaxed with their husband, wife, boyfriend or girlfriend in the car.
The study revealed that women are more wound up by men than vice versa. When driving with their partners, only 32 per cent of women said they felt relaxed, compared to 43 per cent of men.