Just a guess but something will occur to make Shallan think she is not good enough for Adolin, putting him up on some kind of pedestal because he’s not a radiant he wouldn’t be safe with her as she falls further into her disassociate state. This probably occurring almost simultaneously as Adolin speaks his first oath, with all of this occurring around an important event that “seals the deal” for one of the already introduced mains down the “path of good intentions” that ultimately culminates into one of them becoming Odium’s champion. My bet would be Shallan, due to the nine shadows hint...she’s already got three so far, perhaps more with her bout with midnighty mom in the underbelly of Urithiru...