Oh nothing spectacular. BIL came the day before and she didn't want to. No real reason for that, at least to my memory. I think it was that she couldn't get away from work, but she worked remotely so...
Anyway once he left they said it would be too much money in gas for her to come in the second car. If you're good at putting 2 and 2 together this is the morning before our wedding. Wife's aunt and uncle who also live in the Chicago suburbs offered to pick her up Saturday morning but she "couldn't inconvenience them like that." So my in-laws offered to pay for a flight from Chicago to Des Moines (and then later offered a cab, too), but again, she thought it wouldn't be right for her to accept money like that. At that point everyone just gave up. She obviously just didn't want to come which was perfectly fine with me, and my wife, too, once she thought about it.
My wife's other brother and his wife are great. So are her parents. I figure batting 0.6667 isn't so bad.