would_attempt_to_seduce_trigger

would_attempt_to_seduce_trigger = {
	is_adult = yes
	age <= 50
	# Already interested or not a relation
	trigger_if = {
		limit = { has_any_scripted_relation = $CHARACTER$ }
		OR = {
			has_relation_potential_lover = $CHARACTER$
			has_relation_crush = $CHARACTER$
		}
	}
	# Not married
	NOT = { is_consort_of = $CHARACTER$ }
	OR = {
		# Pre-existing schemes
		is_scheming_against = {
			target = $CHARACTER$
			type = seduce
		}
		is_scheming_against = {
			target = $CHARACTER$
			type = courting
		}
		AND = {
			# Sexuality
			is_attracted_to_gender_of = $CHARACTER$
			NOR = {
				# Proactive
				has_trait = chaste
				# Undevoted
				any_relation = { type = soulmate }
			}
			# Compatible or attractive
			OR = {
				trait_compatibility = {
					target = $CHARACTER$
					value >= low_positive_trait_compatibility
				}
				$CHARACTER$.attraction >= medium_positive_attraction
			}
		}
	}
	# Flouts the laws of decency
	would_attempt_to_seduce_incest_trigger = { CHARACTER = $CHARACTER$ }
	# Flouts the sanctity of marriage
	would_attempt_to_seduce_married_trigger = yes
}

As written in game/common/scripted_triggers/00_adultery_triggers.txt.