lose_lover_effect

lose_lover_effect = {
	if = {
		limit = {
			has_relation_lover = $LOVER$
		}
		remove_relation_lover = $LOVER$
	}
	#To clear flags
	if = {
		limit = {
			has_character_flag = can_be_confronted_about_lover_exclusivity
		}
		remove_character_flag = can_be_confronted_about_lover_exclusivity
	}
	if = {
		limit = {
			$LOVER$ = {
				has_character_flag = can_be_confronted_about_lover_exclusivity
			}
		}
		$LOVER$ = {
			remove_character_flag = can_be_confronted_about_lover_exclusivity
		}
	}

	#To remove the object of importance if it exists
	if = {
		limit = {
			has_variable_list = lover_object_of_importance
			is_target_in_variable_list = {
				name = lover_object_of_importance
				target = $LOVER$
			}
		}
		clear_variable_list = lover_object_of_importance
	}
	else_if = {
		limit = {
			has_variable_list = lover_object_of_importance_2
			is_target_in_variable_list = {
				name = lover_object_of_importance_2
				target = $LOVER$
			}
		}
		clear_variable_list = lover_object_of_importance_2
	}
	else_if = {
		limit = {
			$LOVER$ = {
				has_variable_list = lover_object_of_importance
				is_target_in_variable_list = {
					name = lover_object_of_importance
					target = prev
				}
			}
		}
		$LOVER$ = { clear_variable_list = lover_object_of_importance }
	}
	else_if = {
		limit = {
			$LOVER$ = {
				has_variable_list = lover_object_of_importance_2
				is_target_in_variable_list = {
					name = lover_object_of_importance_2
					target = prev
				}
			}
		}
		$LOVER$ = { clear_variable_list = lover_object_of_importance_2 }
	}
}

As written in game/common/scripted_effects/00_romance_effects.txt.