Honestly, the argument over Lyanna’s consent could easily be settled by answering only four questions:
Was her consent voluntary?
Was her consent free?
Was her consent informed?
Was her consent ongoing?
I’m going to set aside Lyanna’s age for now despite how this alone invalidates any argument for consent since Lyanna was a minor even by Westerosi standards and thus incapable of giving consent. But I know that people will come out from the woodworks claiming that “this was how things were back then” which is factually incorrect, and “we shouldn’t apply our modern world’s rules to medieval period” which…. why shouldn’t I? The text calls Lyanna a “child-woman” and goes a long way in establishing her youngness, powerlessness and impulsiveness. It shows how a somewhat similar “relationship” between Cersei and Lancel - which also includes a fucked up power dynamic and an older “partner” using the younger one’s naivete for their own purposes - was devastating to Lancel’s psyche. We argue about the skewness of Dany\Drogo and what it means for the definition of their relationship, we argue about how Cersei and Lancel’s relationship could not be considered consensual despite Lancel saying yes. So why should I ignore the same considerations when it comes to Lyanna and Rhaegar?
However, let’s put that aside for a little while as we try to answer the above questions. Consent is not just about saying yes: for Lyanna’s consent to be valid and accepted, it had to be voluntary, free, informed and ongoing, otherwise it was not consent. But did these adjectives truly apply to Lyanna’s situation?