Love is generally pretty hilarious in Northanger Abbey, in all its forms: romantic, friendly, familial, first love, lust. This book is a lot like a modern day romantic comedy, but one that doesn't get so caught up in the whole dating scene thing that it ignores other kinds of love and relationships. All the kinds of love and relationships in this book are also linked to themes of growth and development. Catherine in particular has to learn to distinguish between manipulative or overbearing love and love of a more considerate and respectful variety. While love is often fodder for comedy here, it isn't totally lacking in more thoughtful overtones.
Despite what the end of the book says, Henry and Catherine actually may have a problematic marriage.
Though he isn't a murderer, General Tilney was still a bad husband.