Because you have absolutely no context for the clip, you nimrod, for all you know there was a scene just before this where Star and Tom had a fight because she told him she was only there for diplomatic reasons and still only had eyes for Marco. Or there could be a thousand other reasons why they start out upset at each other, but the point is people were just grasping at straws saying that his being upset meant it was a flashback when it could easily be explained in other ways.
You guys should have seen this coming, here's what Nefcy said about Starco:
Fan meet and greet with Daron Nefcy.
Around 20 minutes in:
"You can never make everybody happy, there will always be people- but I also think people like to be upset, you know? If you think about what’s the show, what is like- what show would it be if it were just “We’re gonna have Star and Marco get together and they will be like so happy”, the end. There’s no show, what is that show? No one would watch that show. So you have to keep it exciting."https://www.youtube.com/watch?v=bme4NT7FleE
Starco will NEVER happen beforel the series finale at the earliest. So, at least 2 more seasons. They will drag out the dramatic/romantic/sexual tension as long as possible, to keep shippers addicted as well as to satisfy Nefcy's cuckquean fetish.
Probably it will go something like this:>Star has to go to a dance with Tom for royal diplomatic reasons>Ends up enjoying it and having a romantic moment with him>Marco had been weighing whether he should leave Jackie for Star but ends up catching Star and Tom making googly eyes at each other>He has a heart to heart with Star about it and she decides to try patching things up with Tom since he seems to have changed and also so as not to break up Marco and Jackie>Later she learns Tom still has the same anger issues>Breaks up with Tom but Marco is still with Jackie>Tries to pretend she's over Marco to keep the peace