It's usually the red dice that upset me the most. I do LOVE (and hate) those games where you repeatedly get shafted on important dice rolls. Where that 1 hp enemy ship has been arc dodged by my ship, only for my ship to roll 1 hit into 1 evade. Green dice stopped making me sad, as stuff dies, so you just have to focus winning with what you have (winning from behind IS pretty fun). But when you have already lost some ships, and you've calculated the path to victory, and you've set up that TL+F out of arc against a higher PS foe, and it still falls short, that's when it's amazing (upsetting).
I DO know that it happens to both me and my opponent's though, so I don't get too beat up about it anymore. Lots of games are won by even just the small dice rolls working out, those 1 or 2 extra or less damages. You just have to keep focusing on the next steps to victory if you want to win.
I mean, there are plenty of games that LOOKED like I won handily, when in fact, most my dice worked in my favor, and very few of my opponent's worked out. So I gotta expect the same will happen to me sometimes.