Nick Cannon and Amber Rose -- Alone at Last

First it looked like Amber Rose was into Nick Cannon ... then she threw everyone off the trail by grinding on Nick Simmons -- but this new video might tell a different story.

Cannon and Rose hit up Knott's Berry Farm Friday night in Buena Park, CA ... and they were spotted in the front row of Xcelerator -- with all the rows behind them apparently cleared out for some reason.

Now we know it's just a ride ... they're not walking hand-in-hand or anything -- but it's still pretty telling that the two of them went to a theme park together, alone.

Plus, Nick Simmons has repeatedly said he and Amber are just friends -- even though it seemed like BS.