Amok Time

Every seven years a Vulcan is overcome with the need to mate, all other priorities falling away. If they don't get laid in eight days, they enter plak tow, the blood fever, and die. Often they marry at this time, or challenge each other in a fight to the death.

This used to happen only to male Vulcans, but then Enterprise happened. Does this effect Romulans as well? No one knows, but probably!