Lennie felt alone now that he didn't have a mouse because he really liked the feeling of them and he felt upset without the mouse. And they didn't trust him with small animals because he was always aggresive
The old man who started to live over there was starting to feel more comfortable now that he's actually with people and is starting to gain friends. So now he's not that shy anymore he is more confident and can help out more.
George feels like he is alone have no one and was very upset. He realized that in all his life, Lennie had always been by his side actually when he realized it.
The group of white men would always leave Crooks in a room by himself. They never wanted to play cards with them. And so he felt alone and would only read to himself.
Curley's wife starts talking with Lennie, even though she's not suppose to talk to any guy. She realizes that her and Lennie have something in common , which is that they are always alone.
Lennie starts over thinking since people keep telling him that George will eventually end up leaving him. George denies it and says he always going to be by Lennie's side but at the end of it all, George kills Lennie.