Even with the change of surroundings, Lancelot's still pining away for Guenever.
But Elaine has fallen in love with Lancelot. And really: do you blame her?
With nothing else to do (except mope around), Lancelot gets drunk with the butler, and they sit around talking about love.
Lance gets some good news: Guenever is at a castle nearby, and the King isn't with her.
The next morning, Lancelot wakes up, thinking he's in bed with his Guen. Oops: it's actually Elaine.
Lancelot is so upset that he threatens to kill Elaine; she has betrayed him (and remember: he greatly valued his virginity, because he believed that was the source of his super strength and knightly talents).
He's no longer as strong as ten guys (or so he thinks).
Plus, only virgins can work miracles, so now that's gone out the window.
Turns out, Elaine thought up this whole plan—because she loved him.
She wants to have his baby and name him Galahad, just like his daddy.
Lancelot wants nothing to do with this. He tells her that if she has a baby, it's hers, and not his (uh, we think biology will disagree with you on that one, Lance).