Hmmmm… personally i don’t feel like it make my MC “canonically” bisexual 
well, i think it was nothing wrong when my MC found a guy who was charismatically or physically attractive … the author never set Breden as an automatic RO , in fact there were many choices regarding on how we interact with Breden, hence we can always avoid the intimacy choice if we don’t want to romance with Breden for example, male Breden “may” had secretly love my MC , but my MC can still regard him as a friend … there is no need for my MC to distrust or distance himself from male Breden , of course we can’t control what other people might think, but as long as we know who we are…i think it will be alright…
Suzanne always strikes me as someone like Jeanne d’Arc (French version) or Joan of Arc (English version), while there are a lot of “badass” female protagonist in various novels, few had introduce a female chivalrous knight who follow the code of chivalry that usually associate with male knight, except for @Sophia 's Kingdom who also introduce a female version of the noble knight… so that makes Suzanne unique in her own way and always an intriguing romance option especially the scene when she willingly unbuckled her family sword to follow me to Xhaos Land
well… that usually create cycle of violence over and over again 
in future there will always be someone else who seek vengeance against those who commit mass murder by applying another cycle of mass murder again
I am assuming you meant why there was no option for Suzanne to accept us immediately ? actually Suzanne is a knight who want to follow the courtly love affair when dealing with love and romance … you must only kiss her hand and promise her that you will make a proper courting proposal in a more suitable place and circumstances Suzanne will beam with your suggestion and tell you she is eagerly awaiting for your courting proposal where she will accept Hence, it sort of bind the Romance path with Suzanne … For Suzanne , she will only follow the chastity manner of Romance and we cannot simply kiss her lips