marriage_interaction_auto_accept_trigger

marriage_interaction_auto_accept_trigger = {
	trigger_if = {
		limit = {
			exists = scope:secondary_actor.betrothed
			scope:secondary_actor = {
				has_been_promised_grand_wedding = yes
			}
		}
		always = no
	}
	trigger_else_if = {
		limit = {
			exists = scope:secondary_actor.betrothed
		}
		custom_description = {
			text = is_betrothed_auto_accept
			subject = scope:secondary_actor
			object = scope:secondary_recipient
			scope:secondary_actor.betrothed = scope:secondary_recipient
		}
	}
	trigger_else_if = {
		limit = {
			scope:hook = yes
		}
		#Strong hook = 100% accept (unless marrying 1st or 2nd player heir or the ruler and asking for matrilineal/partrilineal resulting in no dynasty children for them)
		custom_description = {
			text = "spending_hook"
			subject = scope:puppet_or_actor
			object = scope:recipient
			scope:puppet_or_actor = { has_strong_hook = scope:recipient }
			scope:recipient = {
				NAND = {
					#Secondary recipient can't be recipient or 1st/2nd heir...
					OR = {
						this = scope:secondary_recipient
						player_heir_position  = {
							target = scope:secondary_recipient
							value <= 2
						}
					}
					#...if the marriage (matrilineal/patrilineal) does not match their gender
					OR = {
						scope:secondary_recipient = {
							is_female = yes
							NOT = { always = scope:matrilineal }
						}
						scope:secondary_recipient = {
							is_male = yes
							always = scope:matrilineal
						}
					}
				}
			}
		}
	}
	trigger_else = {
		always = no
	}
}

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