Marriage may be the perfect recipe for happiness -- but not for lavish Christmas gifts.

A poll by RBS Advanta found that the longer people are in a relationship, the less likely they are to spend large sums of money on each other.

While 53 percent of those unmarried, but living together, will spend over 100 pounds on presents for their partner this Christmas, only 31 percent of married couples are prepared to spend that much.

And it gets worse once you have children -- romantic presents are replaced by practical ones.

For couples together for one or two years, the average amount spent is 101 to 200 pounds, while for those who have stuck it out for longer, it drops to 51 to 100 pounds.

The biggest spender on romantic gifts this year will be a male between 16 and 34 years old who has been in a relationship for one to two years, but does not live with his partner.

The least romantic spender will be a woman married for over 20 years without children, according to the survey.

(Agencies)