Artuhr is in l’amour with Guinevere. But they can't be together because the relationship between a prince and a servant wouldn't be allowed par the king. their l’amour has no chance, Gwen knows that she can't be with him until he becomes king.
The scene in this week's episode reminded me of this. It's not the whole program, only the important parts (and par "important" I mean "the parts Bradley's in")