Two more things have recently occurred to me.

Lizzie stated at the beginning of her videos that the vlogs were part of her thesis project, which was supposed to cover one year, so they'll probably stick to that timeline.

Also... depending on how long the Pemberley arc goes for, Lizzie and Darcy's final Pemberley scene could take place on Valentine's Day.

Which would be, yes, clichéd, but also poetic.