I don't think that they were nodding and agreeing with her feeling bad for feeling bad as far as I remember. I thought they were nodding about the way she felt bad for not asserting herself in the situation. It is difficult, especially for young women, to assert themselves when they are half naked in a room with other people, but essentially she should be able to stand up for herself. Ultimately, if she had been able to say no, or suggested that she was very unhappy, it is quite likely that the situation would not have continued. She recognised that, she recognised that she had laughed along with it and had never said (from what we were actually shown) that they should stop. In terms of her feeling bad for him, the fact that she was laughing only goaded him on, I think, and she felt bad that maybe he would be blindsided by the fact that she was actually upset by his actions. I don't think anyone said to her that she was overreacting or agreed that she should feel bad for feeling horrible - only Sam did in the privacy of the diary room. Skye actually did say 'you don't have to feel bad' (as I recall).
Nevertheless, Sam should have read the situation better. He knows her just as well as anyone else, more than us. He should know better how she may react to such treatment, and he should have understood from the way she was behaving that it was inappropriate to do with her (perhaps not with everyone, but definitely with her). Priya realised this when she saw Aisha's face at the end and immediately went to rectify the situation.
Also, Travis did do the wrong thing. It's her battle, let her fight it. It made her look immature and embarassing to have her boyfriend go and fight her battles for her. He didn't actually listen to her when she said she was unsure whether she wanted him to say anything, and that she didn't know what to do right now. Gross macho, not to mention high-school immature, behaviour on his part.