A 42 years old wrench in need of a husband. Sounds realistic.
Incest avoided.
Maybe disaster wouldn't have caught up to you, if you would have used you incredible isekai knowledge to help your country.
Ahh. Marrying into an enemy noble house....what's it called again? Collaboration.
No logic mistakes worthy mentioning, believable behavior of the MC. Politics seems to be in order (Young nobles are indirectly forced into marrying into the victors noble families.) So far it's a good read. A bit boring, but that might change.