Some 22% of people have considered ending their relationships, a survey found, with family finances cited as the main reason for break-ups.
Other top causes for tension include working long hours, domestic responsibilities, not spending enough time together, and lack of sex.
The results of the study of 2,093 British people were released on Monday January 8 - a date lawyers have dubbed 'divorce day' because of the spike in couples considering ending their marriage after the festive period.
Family lawyer Lorraine Harvey from Slater and Gordon, who carried out the research, said: "People who contact us have generally spent months and sometimes years thinking about divorce, but fears of upsetting their families, being alone or left financially out of pocket have put them off.
"Although it is a happy time for many, relationships which are already showing cracks are likely to buckle under the added pressure and expense that Christmas brings.
"Money is always a common issue and if one person feels that their partner is not pulling their weight financially or at least trying to, then it can very quickly cause resentment to grow."
Of those quizzed by the law firm, 12% confessed that increasing financial pressures could force them to split in 2018.
Some 16% admitted rowing with their husband or wife about money in the past week, with more than a quarter (26%) saying family finances were responsible for most of their marital arguments.
Others cited a lack intimacy as causing relationship problems, with more than one in five couples (23%) saying they slept in separate rooms.
Some 14% said sex often felt "like a chore" and 9% claimed not to have made love to their partner for more than a year.
Almost half (46%) of those asked said they could be driven to divorce if they found out their partner cheated, while 12% admitted hiding an extra-marital kiss from their partner, and 8% owned up to a one-night stand or affair.
Some said they planned to cheat in 2018, with 15% admitting they were likely to kiss someone and 8% saying they may sleep with someone who was not their husband or wife.
Recent data from the Office for National Statistics revealed there was a 5.8% increase indivorces between heterosexual couples in 2016 compared with the previous year.
Overall, 42% of marriages now end in divorce, with the average marriage now lasting 12 years.