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All this time he's been doing things by the rules of wolves/nature. So why now when the woman he made train and get strong to only then aknowledge her as his mate, when she's in danger he has to stop and think which is more beneficial to save between HIS MATE or another woman. Also aren't wolves monogamous, they better not be heading to a harem route. They really wanna pick and choose which wolf traits he's gonna follow.
If he realy though that then why even think "What should I do? I can't save both of them at the same time!" and "If so, which one should I save? The short-tempered blondie? Or...". The naritive of him knowing she could save herself doesn't pass if he contemplated having to choose between who to save.
Or better question, why would you let your man knowingly deceive another woman, have you no morals. We keep looking at the fact she had to give up your newborn part, but she was the former king's lover from the begining, she knew he was stringing that woman along and convinced her to do many things including kill in order to make himself king, and she was completly ok with that. I can't really feel sorry for this woman. Even if she didn't know fully, how did she think the thrid price bacame king just by marrying a higher noblewoman, the crown prince was bound to marry a high noble woman too thus cementing his position. She chose to turn a blind eye for the benifits it would grant her.