Normally I would drop this for the apparently non-consensual (ableit off-screen) sexual relations between the MC and her new husband, but between this managing to be sort of charming in its approach to dragging everyone down into the gutter, the aspect of medieval sexual realism (both the "man and wife are supposed to produce heirs", and "young men are replacements for women on battlefields," respectively), and finally the irony that is not lost on me of how common such non-consensual behaviour is in BL, in the end, somehow, I don't despise this.
I must admit that this aspect definitely still puts a damper on my whole-hearted enjoyment of this, however.
(Conversely, unlike some others here, I think it's totally fine that she's not upset by her husband having a man on the side. Polyamory is a thing folks can support in their significant others, if they are so inclined, no problem. Though having not been asked about it before-hand is, uh... bringing us back to the whole "consent" thing, and lack thereof.)