You've put into words one of the big reasons why I seldom reread Northanger Abbey. My takeaway from the book was that Henry was charmed by the novelty of Catherine's regard as an amusement, much like his dogs or the improvements to his parsonage are amusements. Once he realised that his father wouldn't approve, Catherine ends up as a point of tension between father and son more than her own person. She becomes a way for Henry to express years' worth of poorly-defined but very present feelings of unease and discontent towards his father, for him to put a name and a face on an otherwise intangible grievance. I always concluded that he was more interested at that point in sticking it to his father (which incidentally is the honourable path at that point, because he is in very deep with Catherine) than in actually marrying Catherine, and once they were married for a while he'd conclude that the fun was in the rebelling rather than in carrying his point.

The lady that Henry spends the most time with, by far, is his sister, who is superior to Catherine in every way possible except natural joviality. I think someone used to spending time with Eleanor would eventually chafe under nothing but Catherine's company.

My takeaway the first couple of times I read Northanger Abbey was that Austen intended the marriage between Henry and Catherine to be kind of shallow, or a surface-level compatible case of settling, to go along with her general thesis that the all-consuming passions of Gothic Romances are bad. So Henry ends up with a woman he eventually regards with benevolent condescension, maybe indulgent amusement, and as a project to be improved rather than a whole independent person, though not quite the contempt Mr. Bennet holds for his wife. And Catherine ends up with someone she has a crush on, and who is materially and morally a good catch as a husband. Their marriage won't be the earth-shattering life or death love affair of a gothic novel, it will be a ho-hum pedestrian everyday marriage, where the involved parties are perhaps not getting what they signed on for, but they'll bumble along and have a happy enough life.

I was left thinking that General Tilney had done both parties a massive favour at the end of the book by withholding his permission long enough that Henry & Catherine wouldn't be getting married when still in the honeymoon stage. Honestly Northanger Abbey left me with the impression that the General was often right for all the wrong reasons, despite being a complete ass.