I don't think any Arsenal fans here are bitter. They're sensible chaps and they can see that over the 2 legs, as many predicted and themselves too when draw was made (very pessimistic about it) Barca were the better team, they're just not happy with some decisions.
I understand their frustration but personally I don't even agree with them. I think overall, Arsenal got the better of decisions anyway. Penalty 1st half on Messi gone unnoticed and hey the whole reason Arsenal were leading from the first leg was thanks to a perfectly ON-side goal fro Messi that was ruled out anyway. Otherwise there was even no lead to protect and no bus to park.
So on the balance of things, Barca were the unluckier side with referees anyway. But they have themselves to blame for missing TONS of chances in first and 2nd leg. Had Messi and Co. not been so wasteful, they could've embarrassed the Gunners with a 10-3 score or something overall and send out a much STRONGER message to the rest of the teams.
In regards to the red card debate, I'm personally of the opinion that Robin should've been sent off. For a couple reasons.
1) He was STUPID to get that first yellow in the first place and considering how CYNICAL it was when he basically put his fingers in Alves' eye, he coudl've been sent off right then and there. He lost his cool and temper and did that on purpose and some refs would've sent him off for that though Alves made most of it of course being the dirty player he is. Nonetheless, he lost his temper, gave in to emotion and attacked a player.
2. His excuse of 'I couldn't hear the whistle' is pure BS! You could tell by the way he controlled and shot the ball that he knew the whistle had gone. You're telling me the great forward that is Van Persie would've given a crap shot with his RIGHT foot in that GLORIOUS opportunity ? No... he wouldn't have. He would've composed himself as he was literally one-on-one with not a defender close enough, take a touch towards center and slot it beautifully using that talented LEFT foot into corner of the net. But he knew the whistle had gone.... yet he kicked it having been pissed off still and then of course used the age old I couldn't hear excuse. If he hadn't heard it, he would've performed much better in that instant!
3. This whole ONE second thing is being blown out of proportion. It's not about one second, it's about continuing with play defying the referees' orders and then kicking the ball away which if you wanna count seconds would take longer for ball to come back into play (a ball boy throws another ball back), we're getting too technical and silly here counting seconds, it's not about that. It's about a man being on a yellow card, a stupid yellow card once again failing to control his emotions and costing his team. Him being vice-captain and one of the more experienced players.
If I were an Arsenal fan, instead of blaming the ref, I'd blame van Persie for his antics in the first half and not being to keep his composure. He let Arsenal fans down today as did Fabregas and is did Wenger with his choices. I don't get the Bendtner thing either. Chamakh should've come on instead and earlier too. He was one of the top-scorers in CL last year for Bordeaux and could've won aerial battles if nothing else (he's also faster and more skillful than Nick) against likes of Busquets and nod ball to his opponents.