With the Martin being human and Jon being an avatar arc there are no positive conclusions drawn from it. There is no “love makes you a better person”. It’s just Martin berating Jon for who he has become but also saying that he cares about him (?)
It’s not love that made Jon come back to his senses when he was getting too close to the powers. It was the occasional act of physical violence (slapping/shaking) and I doubt that those particular actions were prompted by love and adoration, rather than Martin’s momentary fear and disgust of fear-influenced Jon. What I’m saying is that any other person could’ve done that, had they been travelling with Jon. Love didn’t play a significant role. We witnessed that others despised Jon for being an avatar as well, and I think it’s safe to assume that they too would do everything in their power to stop Jon from feeding or hurting innconents - but that’s because they hated him and/or perceived avatarhood as violent and monstrous.
Martin’s supposed affection for Jon only resurfaces when Jon tries to go across with his own plan in the last episode, and that one singular act prompted by Martin’s love caused Jon to go with the Web’s plan last minute. The only thing love did for Jon was to strip him of any agency regarding his own life whatsoever. He had to throw away the only decision he could’ve made for himself to appease Martin. His love lost him. His love made him go against everything he believed in.
Love doesn’t fix you, it smashes you into pieces until there is nothing left for you to pick up. The Magnus Archives is not a tragic love story, it isn’t a love story at all. Among many other themes, it is a story about one’s loss of agency. But somehow the narrative completely overlooked that, and instead all that everyone picked up from it was “well they might’ve ended up somewhere else so maybe they’re fine!”. But that is not horror. There is no conclusion drawn it just ends vaguely and hopefully and not at all horror-esque despite it being a horror podcast.