She mentioned the fact that Bellarke were the only couple (platonic or romantic however you care to see them) separated in the finale and…that’s important guys.
Every other couple is still together:
You know what that tells us? It tells us that the show literally does not care enough about the development of those other relationships to show it on screen. You can expect all of those other relationships to grow and change, and in some cases break while others flourish, but we won’t have the opportunity to see any of that happen on screen.
Meanwhile, because Bellarke has been separated for these 6 years, we will get to see every single last bit of their development and it will all be new to us. This is how you build an endgame main pairing you guy.
This can also play into the time jump, because Bellamy and Clarke will have to “relearn one another”, the writers can use this as an opportunity to essentially “reset” Bellamy and Clarke’s relationship.
Previously it was possible to believe (for some) that their relationship was only ever going to be platonic, a reset would allow them to possibly tell the story of Bellarke as more obviously romantic from their “first” (actually second) meeting.
They could also go a second route which would delay the romance a bit longer (although not indefinitely), because after 4x13 there was truly nowhere else they could take their relationship that wasn’t romantic. This option is the one that would best fit the “relearning” scenario, which is why this is the one I think they’re going with.