Seems sus.
MC isn't part of the succession process in her family, because of her pathetically weak health, implying that she likely wouldn't be able to successfully give birth even if she tried. But she is still not allowed to marry outside of her element.
Also she has to consume medicine that she has no idea what it does.
Also also the female lead of the original story is basically a carbon copy of the MC.
Awful lot of suspicious coincidences lining up...