Jimmy- Lana..... Why they are End in smallville?

Why jimmy and lana Has end in smallville? They Are have a lot Of Fans in smallville, aren't they? but why smallville must end their act tragically? Clana must end Because Lana is infected a green crypton.... ChoJim (Chloe-jimmy) Must end because Jimmy has been killed by doomsday...... So, Why they must gone???