lover_breakup_rivalry_chance_effect

lover_breakup_rivalry_chance_effect = {
	random = {
		chance = 1
		compare_modifier = {
			value = ai_vengefulness
			multiplier = 0.5
		}
		modifier = {
			add = 25
			scope:breaker = {
				any_secret = {
					type = secret_lover
					secret_target != scope:lover
					is_known_by = scope:lover
				}
			}
		}
		modifier = {
			add = 20
			has_trait = paranoid
		}
		modifier = {
			add = 15
			has_trait = stubborn
		}

		scope:breaker = {
			every_consort = {
				limit = {
					this != scope:lover
					NOR = {
						has_relation_rival = scope:lover
						has_relation_friend = scope:lover
					}
				}
				add_to_list = other_lovers
			}
			every_relation = {
				type = lover
				limit = {
					this != scope:lover
					NOR = {
						has_relation_rival = scope:lover
						has_relation_friend = scope:lover
					}
				}
				add_to_list = other_lovers
			}
		}
		random_in_list = {
			list = other_lovers
			weight = {
				base = 1
				#More likely to pick another known Lover
				modifier = {
					add = 3
					has_relation_lover = scope:breaker
					save_temporary_scope_as = lover_check
					scope:breaker = {
						OR = {
							NOT = {
								any_secret = {
									type = secret_lover
									secret_target = scope:lover_check
									NOT = { is_known_by = scope:lover }
								}
							}
							any_secret = {
								type = secret_lover
								secret_target = scope:lover_check
								is_known_by = scope:lover
							}
						}
					}
				}
			}
			save_scope_as = other_lover
		}
	}
}

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