More people start divorce proceedings in early January than any other point of the year, research suggests.
More than 30% said infidelity was to blame for divorce
A new website focused on the breakdown of relationships interviewed over 100 divorce law firms.
It found rates of divorce proceedings in early January can be 50% higher than at any other time of the year - with Christmas stress partly to blame.
Insidedivorce.com's survey interviewed more than 2,000 people, with 30% citing infidelity as the cause of divorce.
'Lack of sex'
Lawyers said Monday was expected to be one of the busiest days of the year. Traditionally, the first full week of business after the new year sees many people starting proceedings.
Insidedivorce's research found the second most common reason for a marriage splitting was falling out of love, while nearly 16% of women cited abuse, the site said.
One in 10 married couples admit they have no sex at all, with men in particular citing lack of sex as a key cause of problems.
Divorce lawyer James Stewart of firm Manches LLP said Christmas often highlighted the flaws in a relationship.
He said: "Extra time together can force problems that already exist in the relationship to come to a head.
"We're expecting this to be our busiest day and indeed our busiest week."
More than half (54%) of those who blamed divorce said they had discovered their partner's infidelity themselves, while one in five people confessed, 4% said they were told by the other man or woman, and one in 100 were told by text or letter.
Falling out of love was the reason cited in 26% of cases - while more than 21% of people, including 6% of men, said abuse was a major cause.
Paula Hall, a relationship psychotherapist for Relate, said: "With the exception of abuse, the reasons cited in this report are common symptoms of a relationship in jeopardy."
Other key problems mentioned included financial disagreements, alcohol or drug abuse, debt, and careers or hobbies taking priority.
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