Research in the US state of Washington has pointed to surges in divorce filings in March and August each year. 

In the UK, we tend to find that there are similar post-summer and post-Christmas peaks in September/October and January/February, coinciding with the times of year that families tend to spend most time together. It does seem to be the case that a bad family holiday or a difficult Christmas can often be the final straw that leads an unhappy spouse to conclude that their marriage is at an end.