Many people hate swampy, sticky August, but to some, it’s an especially bitter time. A new working paper finds that, in addition to March, August is the month in which divorce filings peak.

For the paper, the University of Washington’s Brian Serafini and Julie Brines analyzed the 15 most recent years of divorce filings in Washington, a state whose records make it easy to collect divorce data. Here’s what they found:

Divorce Filings by Month

Data from Washington state, Nov. 2001 - Dec. 2015 (Serafini and Brines)

These results are yet to be peer reviewed, but they are bolstered by some nation-wide, anecdotal evidence. Online searches for “divorce” and “child custody” surge early in the year, peaking in March, they point out.

The authors speculate that unhappily married couples schedule their divorce filings around both the winter holidays and Valentine’s Day, as well as summer vacations. (More Americans vacation in July than any other month.)

There are a few explanations why people might time their marital dissolutions this way. It might just be too difficult to announce a divorce around family-oriented Christmas time, especially if there are kids involved.

But the authors think the more likely reason is that people decide their differences are irreconcilable right after a big trip. It could be that people don’t want to ruin a family getaway, or that vacations are so stressful they drive the already-dissatisfied to divorce. (“I told you to pack your suitcase last night; now we’ve missed the train!”)

Then there’s the “broken promise” hypothesis. “People are discontent with their marriages, they look at vacation as an opportunity to give it one last shot, and what they were hoping would happen didn’t occur,” explained Brines, an associate professor of sociology.

It’s not you, in other words; it’s your failure to print the boarding passes.