It took him a long time to forgive Sam. Look at S5 - there is a lot of tension for the first half of the season.

Also Cas BROKE the wall in Sam's head - he knew that it could kill him and he did it anyway. In no way would Dean just be able to forgive that - especially not in the span of two episodes. I feel like people who say that Dean should have just forgiven Cas are kind of kidding themselves. Look at Dean's history and tell me one person that he has forgiven in such a short period of time, especially when they hurt Sam [or John, or Bobby, or Lisa, or anyone he's really cared about] on purpose.

ok I know cas did those things but he felt abandoned by dean and sam no way is that any excuse for bringing down the wall in sams head,but he felt alone without anyone and I dont think he should have teamed up with crowly in anyway hes a demon ,but i do think that dean shouldve forgave him not boom just like that no but he shoudve at least let him know he was still his friend!

I truly understand Cas in this situation, he didn't see any other way to win this war and BTW he wasn't doing that for himself..and to count on Dean and Sam?.oh please they called him whenever they needed him, when did Dean ask Cas for his war and how is going on with it, and offered help? Right, NEVER. And now we blame Cas for what he did? I'm saying it was good what he did with Sam but he just didn't see any other way. Maybe if Dean somehow just a little made so interest what is happening with civil war in heaven and somehow helped Cas maybe he would change mind. And we all seen why he didn't ask Dean at first and can we blame him? No, because Cas knew Dean wanted that apple-pie life and he just could just step to his front doors and say "Hello, Dean. I need you help." You really think Dean would go to help him and leave Lisa?
And should we start to count how many times Winchesters had teamed up with deamon? Everyone makes mistakes and Cas wasn't exception. I could annalyze everything what Cas done from psyhological point of view but I am afraid I'll write way too much.

totally agree with you inetux...Cass was alone and must saved the world..Nobody took care of him during one year...dean with lisa, bobby and sam...And cass? noboby called him and everybody knew that he still in trouble in heaven (sheriff of heaven)...Everybody let him down...dean, sam and bobby survived because cass saved them...it's time for them to save cass...he maybe can help sam anyway...

I'm not sure. On the one hand, Cas was kind of backed into a corner. It was either help Crowley and try and double cross Crowley before Crowley double crossed him, or wait for Crowley to go to Raphael and hope that he and the boys would be able to stop them. Which, as we see in the start of season seven, wasn't going to happen. There really wasn't a whole lot of options available to him.

On the other, he crossed a lot of lines that he really didn't need to cross. He didn't need to break Sam's wall. He didn't need to steal from Bobby. Hell, in a way, he didn't even need to lie to the boys about anything at all.

I just... don't know. I know eventually Dean would have forgiven Cas. But should he have? I don't know.