What a development…
@heml8ck thought up to this point is mixed. If the holy knights
all knew that she was a woman, then my own personal guess was that Julius thought that an impure (labeled as such by society because he was a sacrifice for the demon clan amongst other things) would make him ineligible to marry Roel, amongst other issues pertaining to her oaths and covenants to the church, her views, amongst other things. That said, it may well he possible that he's reacting because he thought that she was a man in her past life, and he's too unyeilding to
swing that way despite the obvious…
I'd consider this latter scenario just plain bad writing, unless it was to show the complexities and biases of existence, and played out in a believe and effective fashion. That said, I feel like the more likely scenario would be Julius thinking that as a holy knight, Roel would not want to be with him further, and now that she/he's gotten back to the church, it would be inappropriate for Julius to continue being with him because cinnamon roll Julius has internalized the predominant views about a person in his position. In other words, how could he
dare to consider marrying their effective "saint" as a corrupted and stained existence?‽!
I'd imagine in this case that Julius could care less about what gender or sex Roel had in eir past life, and instead would be concerned about the present situation and how poorly matched an unacceptable he considers himself towards Roel. (Whereas Roel holds diametrically opposed views to this—I imagine that Roel will have to knock some sense [metaphorically or literally] into her plucky heroic shadowy male lead with a bit of an emo vibe so he stops beating himself up.)
We'll see what comes to pass soon enough.