I *suspect* that may have been a bit of a joke on his part - iirc, his wife wasn't Cathar and he was, which made his marriage something of a trial, and the other woman of the same name he claimed he'd meant to marry *was* Cathar, so it might have just been some bitter irony about how much happier he'd've been if he had married her instead.

On the other hand, most marriages between low-ranking nobles seem to have been long-distance and sight-unseen and fairly hasty, and given the general background level of incompetent hijinks it's entirely possible he really did just get mixed up and send the messengers to the wrong castle and then he couldn't honorably back out, after all.