t began rather early. This is pre dating times and all. But think of from him not paying attention then she did that thing of needing to raise her robes to wash clothes and they both blushed. Then her calling to him on the black ship after thinking she would die. then seeing the killing of white lotus leader by Rugi. Even if it was just that and we assume nothing else ent on during the years between then and now, thats more significant a bonding experience than most people go through.