Sylvia, bless her heart, was innocent and childlike, but quite stupid and rather sleazy, and her beauty showed to be her curse. Everybody imposed their concept of who she was and who they wanted her to be, especially Marcello who said something along the lines of "you are a lady, mother, lover, and house." To which she ignored as it meant nothing to her. They see her as somebody with so much depth and whimsy, when in reality, she only welcomed the attention because that was her form of fulfillment. Her boyfriend was much more aware of this as he became more and more frustrated by how infatuated people became with something that wasn't even there.
Maddalena was a bitter woman, for what we will never know. She was self-deprecating and destructive because she viewed herself as such a low person, which is maybe why she kept Marcello around. She refused to pursue what she loves because she was punishing herself for whatever reason. She refused to be serious because she was afraid to look at herself seriously because she was fully aware of how lost and broken she was.
Steiner reminded me a lot of the great Charles Foster Kane, except he was much better at managing his discontent life. In retrospect, his character was quite puzzling to me. Maybe it was Fellini's way of saying even fulfillment can't fulfill. That achieved perfection leaves nothing left to fight for. Though it disgusted me that he would be so selfish to take his children's life and leave his wife widowed and depressed. He was a sicko. He should have just taken up a hobby.
Emma I related to the most. She was so disillusioned with how she wanted things to be that she believed her own lies...