failed_befriend_opinion_critical_change_effect

failed_befriend_opinion_critical_change_effect = {
	$CHARACTER$ = {
		add_opinion = {
			modifier = disastrous_befriend_attempt_opinion
			target = root
		}
		if = {
			limit = {
				NOR = {
					has_relation_potential_rival = root
					has_relation_rival = root
				}
			}
			hidden_effect = { set_relation_potential_rival = root }
		}
		else_if = { #If you already are potential rivals, you have a chance of becoming Rivals
			limit = {
				has_relation_potential_rival = root
				NOT = {  has_relation_rival = root }
			}
			hidden_effect = { remove_relation_potential_rival = root }
			set_relation_rival = {
				target = root
				reason = rival_disastrous_befriend_attempt
			}
		}
	}
}

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