I don't really know if it's a plothole, but in canon, Sarah goes from being this tough, independent woman in old series to being unable to get over her love for the Doctor in new.

It's cute and all, but in some ways, it kind of isn't her. I can see her falling in love with him and loving him forever, but Sarah's life wouldn't stop cause the Doctor is gone. I know a lot of people have had issues with that.

*pokes new series and it's overly done romantic tendencies*