I think Chris Marshall married one of the American girls and goes and lives in the States.
Emma Thompson marriage turns cold. Alan Rickman remains faithful but she goes on to have numerous affairs.
The PM and Natalie marry and fill no 10 with nappies.
Keira Knightly separates from her husband and realises she's in love with his BF. She finds him and he's happily married.
Colin Firth ends up marrying her sister.