As I have posted previously on this board, I am puzzled about why Wickham, who was going AWOL and wanted to avoid paying off gambling debts, wouldn't just slip away quietly during the night. It doesn't seem likely he would confide such a plan to Lydia, because she's a gossip and she is staying in his colonel's home. Maybe it was Lydia's idea to run off -- she may have told him that her uncles had money, or maybe she thinks her family is better off than it really is. I am sure Wickham had no intention of marrying her; he may have been planning to ditch her and to extort money from the family to keep the whole episode quiet. I have to think that he was so desperate that even the relative pittance Mr. Bennet could offer would have looked good.