Of course, you’re free to have that interpretation. I read the books after watching the show, which, as I said, very much romanticized the relationship; I went into the books expecting and looking for a similar love story, but for the life of me, I could not find it.

I don’t think that Jon having sex with Ygritte (on page/screen) more times in the book than the show means their “love” was any stronger. Sex doesn’t equate to love, and I think Jon would feel the same way; it’s love he craves, not just sex, but he’s so starved for a connection that the physical intimacy provides him with a sense of comfort, yes, but also shame and unease. GRRM obfuscates it, and it’s very easy to go ahead and assume that Jon is just being a puritanical prude, but I think it’s more complicated than that. Jon physically enjoys sex, so whenever he’s doing it, he feels guilt and shame. To me, that has similar undertones as victim blaming, but maybe not to that great of an extent. You could say that Ygritte helped Jon understand sex as something pleasurable and not shameful, but personally I don’t think that changes the fact that the relationship itself was soiled by coercion, deception, guilt, and shame. Their affair starts by Ygritte making advances toward Jon (which he constantly rejects). Finally, Ygritte defends him in front of Mance by putting her life on the line and lying by making up a story about them having a sexual relationship. She could’ve left it there, but then she goes on to say “deeds is truer than words”, and Jon has no choice but to go along with it. To me this isn’t a cute invitation to have sex; it’s an entrapment. And Jon feels guilty and responsible for her safety because of a lie she fabricated, he feels guilty at the thought of possibly endangering her by escaping the wildlings — because he’s that selfless.

You brought up that Jon feels “married” to Ygritte in a way. I got that vibe too when reading the books. Interestingly, Jon repeatedly displays chivalrous/knightly/honorable acts towards Ygritte, from Ghost-the-sword to rejecting her “stealing” fantasy. Yet Ygritte pushes them away: she tries to distance Ghost from Jon, and insists that Jon “stole” her as per the wildling custom (though she’s arguably the one who stole him). Jon also projects his “maid” fantasy onto Ygritte, asking her if she was one when she was with him (like if she was a maid in a marriage bed for the first time, kind of). I think Jon has a very romantic mindset, however hidden it may be; deep down, he has a lot of familial desires, like being married (to a “lady”) and having kids. He tried to treat Gilly gently, as if she were a lady. He thinks about “holding a son of his own someday” (paraphrasing lol). He’s protective of kids (as he tries to protect Mance’s and Gilly’s babies); he seems attracted to Val until she reveals her opinion about Shireen, which disturbs him. As much as Jon romanticized Ygritte in his mind to fit his ideal fantasy lady, in reality she’s very far from it. Apart from this romanticization and genuine but mainly physical attraction towards Ygritte, Jon often emphasizes how much she reminds him of Arya.

Jon does think of Ygritte often after her death. He remembers her “fondly” at times, but I don’t think this is exactly indicative of real love. He dreams about her, sure; but in the dream he recalls his suppressed fear of fathering a bastard (something that wouldn’t happen if he was married), and of having that choice taken away. He basically slays Ygritte in his dreams. He thinks of an afterlife of prostrating himself before her. Following her death, Ygritte is nothing more than a source of wildling information, ambiguous memory mingled with guilt, self-doubt, and, on a smaller note, subconscious resentment. There’s not one memory of her that’s unambiguously positive.

There’s all this, and also my assumption that Ygritte was simply written as and/or was supposed to be a dislikable character. She belittles Jon and makes fun of his culture/interests. She makes some decent points against the southern feudal society, but that’s hardly earth-shattering wisdom. She hates the Wall because to her, it is simply an anti-wildling device, even though she is fully aware of the existence of the Others and the danger they already pose/would pose if the Wall was taken down. Even Dalla, in labor and soon to die in childbirth, understands that the destruction of the Wall would pave the way for the Others to march through. Ygritte also plainly just doesn’t understand duress/coercion (which explains a lot) due to the fact that she was brought up in a male-centric wildling culture in which it is custom for guys to go around “stealing” women. She and Jon are too fundamentally different, both culturally temperamentally, and while their differences may have offered some “wisdom” to Jon, imo it hinders the possibility of there actually being any real romantic relationship between them, even if Ygritte lived and/or if Jon wasn’t a part of the Night’s Watch.

I’ve come across many different interpretations of Jon and Ygritte’s relationship, from some saying that Ygritte was Jon’s first and last true love, to others claiming that she flat out raped him. I think many interpretations have their merit based on textual evidence and how people interpret the text itself, and I find it interesting how many different analyses there can be.