Thor has only one excuse: he needed time-out to think about the latest incidents. I think he had never noticed the brother’s independent and strong temper before (and also his fidelity to duty), considering him soft and yielding, as long as the brother was on his side. Then Loki began to act against Thor, and that was totally unexpected for Thor (it seemed to me that Thor didn’t understand the reasons of the banishment at all, not only of Loki’s “sudden” riot). Besides, Thor saw the real strength of Loki and was, well, a little bit shocked, and considered the brother completely changed. He didn’t understand the reasons of this transition. And while he didn’t understand, he couldn’t deal with him.
Nevertheless, Thor felt that something was wrong in Asgard, and during the “Dark world” tried to find out, what was it; and finally he saw the whole truth about Allfather with his own eyes. Thor found himself in the same position as Loki in “Thor-1”: alone, persecuted by all Asgard, but still trying to prevent a disaster which was going to happen because of the mistakes of Allfather. At that moment Thor became able to face his brother again. Because he began to suspect that the brother was not as wrong as everybody thought about him.
Thor is so desperate keep his father's love and attention that he rolls over and does whatever his father wants him to. He knows that if he resists, he'll be abandoned so he doesn't, at least not until he desperate and something means more to him than his father's love and approval. This is the case when Jane’s life is in danger mother Frigga is killed; saving Jane, avenging his mother’s death and protecting Earth is more important to him than keeping his father’s approval. Unfortunately, I think this might be one of the main reasons that he doesn’t visit Loki in prison, there’s a deleted scene that suggests that Odin has forbidden anyone to visit or talk to Loki (who does that?! He’s still family and expecting him to be in solitary confinement is cruel!) but Frigga breaks the rules and talks to him anyway, Thor is too afraid of gaining his father’s anger that he doesn’t visit or communicate with his brother until he’s so desperate that he’s willing to break those rules to beg Loki for help. At the end of the movie, Thor no longer cares about his father’s love and approval so he basically tells (who he thinks is Odin) in the most respectful way possible, “screw you dad, I’m going to do what I want, not what you want! Loki was right; it’s not worth it to fight for your love and approval!” Loki finally get the throne and Thor gets to defend Earth with the Avengers with Jane by his side, everyone’s finally happy and gets what they want (except for Odin because he’s mean.)