I don’t think this is the end for RumBelle. I don’t think they’ll officially be back together until at least season 5 at the earliest, but they’ll be working towards a reconciliation.
As RG said, I believe this episode signalled the beginning of the end of ScarlettBeauty. If the writers wanted ScarlettBeauty to last, they would’ve taken the time to flesh it out. It’s merely an obstacle for RumBelle.