@Annie have you heard of marriage of convenince? Though i also know the spoiler, It is kinda like that atleast to what it looks like that can be assumed, it looks like he married her cause she is his exclusive guide and it is convenient to bind her so she is always there when he needs her. Anyways many marriage have one sided love or no love at all, and they get married for different reasons and these types can be because they need something from that person.