According to the ON he truly loved her, so why on earth did he run off with Maria - 'because he could not help it'? That just makes absolutely no sense to me at all. But I think it all worked out for the best - Henry would have been bored with Fanny after awhile, and Mary would have spent her days trying to change Edmund. Those couples just weren't suited for each other. And I think in JA's other novels when someone changes for love, they have a sound moral compass to begin with. Since Henry doesn't have this (because of the villanous uncle, as jeffrey pointed out), he isn't capable of changing for the better. He will remain as he ever was, with just the memory of the 'ideal' woman he could have had, but lost. Kind of like W from S&S, but there is no mention of him seducing young girls, so he's not quite so bad - it's as though JA led us along all the while, making us wonder if Henry is capable of changing, because he had it in him if he wanted it, but, but, but.....