I understand that as BJ's previous marriages x 2 were not in a Catholic church, they are not recognised by the Catholich church. Boris was baptised as a Catholic but became Anglican at Eton, he's since been taking instruction with Carrie prior to the marriage so has presumably become Catholic again but actually doesn't need to. Carrie is unmarried and a Catholic and BJ is legally free to marry. What's the problem?
Harriet Sperling's Wedding Dress
and really bloody CRUEL