One in three couples say the biggest strain on their marriage is finances.  A survey conducted by asked couples what issues were most likely to end their relationship.  Excess alcohol was the second-most cited strain, followed by in-laws, household chores like cooking, and gift-buying.  

12% of respondents said that simply spending more time than normal around their partner, like during the holidays, causes the deficiencies in their relationship to become more apparent.  The site also notes that the first Monday of the New Year is usually the most popular day to file for divorce.