I’ve thought about how to answer this for a little. And this might seem like an odd tangent to go off on, but just hear me out.
I am of the opinion that Jon is absolutely Rhaegar and Lyanna’s son, and that their relationship was consensual (ymmv on how manipulative it was, but I believe it’s supposed to be a tragic romance). And I’m assuming the show will “confirm” it if not this season, next. They’re really not being shy about the nods.
How explicit is it in the books? It kind of reminds me of Dumbledore/Grindelwald where on first read you may not see it, but on reread it’s totally there, to the point where you can’t believe you missed it. And like understanding the romantic nature of the Dumbledore/Grindelwald relationship, knowing R+L=J majorly enhances the narrative.
See that’s the thing about “R+L=J.” It’s not like some big “whodunnit?” puzzle for the readers to solve. It is an element of the narrative: one that is thematically central to Ned’s story, as well as potentially significant for Jon’s role moving forward. The latter is something I can only guess at, but the former…it’s about Ned’s internal vs. external honor. This secret was killing him, but he knew it was the right thing to do despite the fact that it besmirched his honor and caused strife with Catelyn. And then Ned poetically does the exact same thing to save Sansa, which ultimately is what kills him (it’s also worth noting there are major parallels between Lyanna and both Stark girls).
Ned’s AGOT narrative is like, ALL about this, too. His arc was never a simplistic “honor gets you killed,” which are the words that D&D put into the mouth of Stannis last episode. And that’s what’s kind of pissing me off about what’s happening with R+L=J on the show. It’s once again D&D’s simplistic understanding of things.