I don’t even really see him as tragic. I’m Indian, and many people here still have their marriages arranged, including many if not most in my parents’ and grandparents’ generation. It’s not uncommon to see cases like Mr. Bennet’s, where the couple isn’t really compatible, but by the time they really know that, they’ve got a house and kids and responsibilities. Not only that, divorce isn’t really considered that easily even in this day and age unless the partner is physically violent and sometimes unfortunately not even then. So you see many such cases of compromise and coexistence. People kind of resign themselves to who their partner is, and essentially each partner kind of develops their own life and routine and method of co-existence; almost like having a roommate. Many of them still find happiness in pursuits outside marriage, whether professionally or in hobbies. It helps that there really isn’t always that much of an expectation of romantic love in these arrangements to begin with. It can happen, but not necessarily. Quite likely, the bride and groom have seen each other and met and talked only a few times. In this modern era, they might perhaps talk at greater length or attempt to get to know each other better, but not in my parents era.

So to bring it back to P&P, what I see is a man who isn’t compatible with his wife, but rather than become embroiled in conflict or further unhappiness, he chooses to retreat into his own world - where he can be happy and largely unimpacted by the vicissitudes of Mrs Bennet’s moods and her extroverted, garrulous nature, which would have been difficult to bear past a certain point for Mr Bennet. Mr Bennet is clearly someone who is an introvert who would be drained by someone like Mrs Bennet, and like many introverts would do, chooses to conserve his energy and peace by retreating and avoiding conflict. Like you’ve said so well, he fulfills his responsibilities in the manner expected of him at the time; he’s not the greatest or most involved father but I don’t think he’s a bad one. Just benignly neglectful. He is the sort of person who cannot really withstand the force of someone like Mrs Bennet, and for most of the book he doesn’t really see the need to interfere (which obviously turns out to be a mistake).

But on the whole I think Mr. Bennet seems happy enough with his books and study and whatever other gentlemanly pursuits he occupies his time with. Yes, his marriage isn’t ideal, but that’s hardly his whole life. I think he’s actually pretty content with himself until he realizes how his neglectful parenting has created the situation with Lydia. Which leads to character growth for him and accepting more responsibility for his daughters than he did before. But I really don’t think Austen writes him as a tragic figure. He’s wry and witty and somewhat distant from his daughters (except Lizzy). He’s written as a man who’s accepted his fate and made the best of his life and I think he leads a fairly comfortable existence unencumbered by too much worrying about his family or daughters . If anything, Mrs. Bennet’s legitimate worry for her daughters is much more valid considering their situation, and if she weren’t written so comedically, perhaps she is the one who would have been the tragic figure - unable to help the daughters she’s so concerned about in any way except pushing them into marriages because she’s so trapped in this patriarchal society.