Annnnd....dropped. :/
I'm sorry, but I can't stand when a plot is driven by stupidity. Yes, she can marry Sir Heiden. No, it wouldn't be a bitch move. All she has to do is explain her plan to them that it'd be a marriage in name and only for a year. After that, she can divorce him, and Sir Heiden and Seira can marry after that. It's an extremely simple solution to their problem. Afterwards, as she said, she could easily go on to find herself a partner she actually likes. So what if divorce isn't well taken in Sofen? Sir Heiden and Seira's livelihoods are on the line. Yeah, someone else could get their lands, but there's no guarantee that these two will keep their positions/jobs. I'm pretty sure that takes priority over old fashion conventions.