Fwiw, I think that's typical of all Austen novels. Emma is probably the only one that doesn't feel rushed to me, and even then, once the love confession happens it's just a matter of tying up loose ends.

I've always read Eleanor's sudden marriage as another element of satire. We're told the whole book that Catherine is not exactly a classic heroine, and right at the end Austen is kind of like "you just read a whole-ass book about our quaint and naive little heroine who imagined she was in a Gothic story, but all along Eleanor would have fit the mould of a classical heroine what with her tragic romance so much better lol".