They were flirting in the pilot. It was like they toyed with the idea and then just dropped it. When I watched the pilot, I thought that we might get a little more Finn/Octavia than we got.
I think deciding that they wanted to keep Jasper around maybe shifted the direction that they were initially going in.
I thought it was interesting how most of the season, Finn/Octavia agreed on how to handle things so at the very least, I could see maybe more of a friendship developing between them.