I know, but this series isn't exactly big on following the original legend. I ship ArthurxMerlin, like a lot of people, but I really like Gwen and she and Arthur were adorable IMO.

Besides, it's BBC One. However much we wish for it, ArthurxMerlin won't become canon. There is one solution that has been proposed in quite a few fanfics, namely, Gwen and Arthur marrying because he has to marry and he trusts her much more than any of the noblewomen who are only out to become queen. It leaves both the possibility of MerlinXArthur and GwenxLancelot open. ^^