There's something so funny about both of them putting on a show in the middle of the forest to trick the King into thinking that they hadn't slept together. Imagine if they were both bad actors, like one of them has lines written down somewhere. There's almost no way Yseut said the little lie about loving the man who took her maidenhood just off the top of her head. It seems she had been stewing on that one for a little while. 

This isn't a very analytical journal, but reading the whole section just kind of made me laugh, even though the characters were at risk of serious death if they were found out.