Looking back at S&S we see that Edward and Col. Brandon were very gloomy and operating under oppression of spirits. Edward had a bleak future ahead as we've discussed some time back in the GR. And from the moment we met Col. Brandon he was distressed over the disappearance of his ward, though we didn't know it. With the exception of glimpses of Edward's sense of humor, we didn't get to see much of their personalities.

Elinor could see the true worth of both of these men, while Marianne at first could see nothing to admire. Along came dashing (yet dastardly) Willoughby, whose lively manner which it was no merit to possess. Surely there is nothing wrong with a lively manner; it is just not proof of goodness as Marianne (and to some extent all of them) believed. Willoughby sails along in the story gaily unconcerned with the trail of destruction he's left in his wake.

In ch. 49 we get to see Edward finally happy. His sense of humor makes an appearance again, and we see his personality start to come through.

Poor Col. Brandon, we have learned of his goodness throughout but we don't get to hear him speak of his happiness. We only get to be told of cheerfulness ch. 49 he had little to do but to calculate the disproportion between thirty-six and seventeen, brought him to Barton in a temper of mind which needed all the improvement in Marianne's looks, all the kindness of her welcome, and all the encouragement of her mother's language, to make it cheerful.
According to the Ellen Moody calendar (almost 1 1/2 yrs after Edward & Elinor engagement)
1799 September. "Two years" after Marianne had declared Colonel Brandon to be too old to marry, she marries him. She is 19, Brandon 37.