It’s common to hear about the so-called “honeymoon period” for newly married couples, but Ohio State University researchers found that conflict levels don’t generally change much over the course of a marriage.

The study, which was published in the Journal of Family Issues, followed nearly 1,000 couples for 20 years from 1980 to 2000 and saw little change in their conflict levels throughout that time. Researchers said there was a slight decrease in conflict among low-conflict couples in the final years of the study, during which high-conflict couples saw an increase in fighting. However, the researchers said, these changes over time were small.

Researchers said the marriages with the lowest levels of conflict and the highest levels of happiness consisted of couples who made joint decisions and believed in traditional, life-long marriage.

“People who believe marriage should last forever may also believe that fighting is just not worth it.  They may be more likely to just let disagreements go,” said Claire Kamp Dush, lead author of the study, in an Ohio State University release.