I think the only way to treat the prologue in the manga, is accept that it's being told through Tia's point of view. Based on everything we know about Ruve's side of things, we can say she's an unreliable narrator on those events. Some would disagree of course, but it doesn't change the fact that the prologue is nowhere near to the events that actually happened.
This is seriously one of the reason why I sometimes HATE the management for mangas. Most manga cut out the important details from the light novel. You see it a lot in Chinese/Korean mangas. Just botched stories and half the time you feel like your missing something cause they reference something without giving much details. But if you read the light novel then you get the reference

I think the manga did an incorrect job of portraying Ruve the way he was in the beginning. The manga never showed Tia's other insane side, never portrayed their misunderstanding over the miscarriage. The manga never showed Ruve's desperation to save Tia from execution, wanting to free her (instead, showed him laughing, I don't get it)
The manga never showed his contrite and yearning to atone to Tia, to reveal his lies about her fathers death being a result of his anger over her hysterical laughing, thinking she was being glad over her child's death. She never communicated as well. Let alone both of them being pawns. But oh well.