Elaine decides to pack up little Galahad and head off to Camelot to take on Guenever on her own turf.
Meanwhile, back at Camelot: since Arthur is now home, Guenever and Lancelot have to do an awful lot of sneaking around to get together. This makes Lancelot feel really shameful, because he honestly loves Arthur.
We find out that Guenever has a kind of weird sixth sense that even she is not aware of: she actually already knows on some level that several really bad things are going to eventually happen.
Because she's so jealous of Elaine, the baby and Lancelot's love for Arthur, Guenever becomes more and more cruel and petty to Lance.
Arthur just tries to stay out of this situation, because he's basically a good-natured guy who hates petty things like jealousy.
He, however, doesn't even know that his wife and Lancelot are sneaking around behind his back. He's never seen any proof of this, but isn't really going to go digging to deeply, though, either.
In other words, he's hoping to remain ignorant, but unconsciously knows that the two are sleeping together.
Arthur does make one attempt to get it out into the open: he asks Lancelot why he's looking so miserable.
He quickly follows this question up with a more specific one about Elaine, though, because he really doesn't want to get the truth about Lance and Guen.
Lance spills enough about Elaine and her plot and his misery for Arthur to accept. He still doesn't want to dig too deeply.
Guenever comes after Arthur leaves to tell Lancelot that Elaine is on her way to Camelot with the baby.
The Queen tells Lancelot that he can't have anything to do with her while Elaine is there; she wants him to be free to dally with Elaine, because—after all—she wants them to be able to marry if he wishes.