But equally, happy people are more likely to make happy marriages, according to Dr Robin Russell and Dr Pamela Wells, of Goldsmiths' College, London.
Their study of more than 1,200 married couples showed that the quality of the marriage was the most important predictor of happiness, suggesting that 'good marriages do tend to correspond to the Mills and Boon ideal', Dr Russell said.
The only other predictor that stood out in the study was whether people worried a lot, the psychologists said.
There was also 'just a hint that having children around makes you a bit less happy', Dr Russell added. 'Marriages tend to go to pieces when the children are around, but, when they leave, your relationship picks up again.'
Factors which affected the quality of the marriage included relations with in-laws, and how satisfied people were with their home. Whether people were neurotic was also important - those who were proved less happy, had a less satisfactory marriage, which lowered their happiness still further, and made their partner less happy by lowering the quality of the marriage as seen by the partner.
But in terms of predicting happiness, the quality of the marriage was 'of paramount importance', the psychologists said. 'It does seem you can have love in a garret,' Dr Wells said. 'Material things seem not to matter too much.'