You know there's another reason I really want to believe Jon has ulterior motives when it comes to Dany, that he didn't just stupidly fall for her like every other man and gave her the North because of those feelings. It's not only to salvage whatever's left of his character, but also because him not being fully or genuinely in love with her bodes well for his chances of survival. And not just because it would mean he finally learned to the play the game (though of course, that skill is also key to his future survival).
Giving him a second epic but tragic love story à la Ygritte kind of reads to me like one last hurrah before his demise, a bit like Robb x Talisa. On the other hand, if his relationship with Dany proves to be something less than straight up romance/true love from his POV, I'd say that's a good sign that Jon will survive past the last episode, that his chance at love and happiness is yet to come. The same goes for Sansa. The fact she has yet to experience genuine romantic love gives me hope it's still to come. Like Arya said, their stories aren't over yet.
In contrast, you have Dany who I'm almost positive won't live to see the end of the story. Her being truly in love with Jon makes sense narratively, giving her (and the audience) the false impression she's getting the whole package: the North served on a silver platter, the love of the brave and handsome hero, even a pregnancy most likely. Before pulling the rug from under her feet with RLJ and/or Targbowl and/or Jon's betrayal and/or a miscarriage and ultimately her death. It would also make Jon's potential "betrayal" that more painful. Just to REALLY pull at our heartstrings, you know?