Curley’s wife is a loner as she is the only woman on the ranch. She does not have any one to confide in and has been misled in her past. She is convinced that her mother stole her letter from the film producer, and is cruelly deluded by the man at the dance hall with regard to her future in film. Whether she truly believes she ‘could’a been in pitchers’, she is certainly aware that her life could have been much better than it is, and reveals her true dislike for her husband.
Like Crooks, Curley’s wife finds Lennie fascinating as she can reveal her innermost thoughts in his presence without being judged or derided.
Curley’s wife dreams as much about her past as her future – she reflects nostalgically on the meeting with the ‘film producer’ and the life that she could have had.
You can clearly see in this chapter that Curley's wife is a dreamer. You can see this in her telling Lennie about how she could have been a movie star. It seems clear that the people who told her that were conning her, probably to try to get her to sleep with them. But she believes it and that shows me she's a dreamer.
As far as being a loner, this is less clear to me. But you can argue that she is a loner given that she is seeking out someone like Lennie to talk to. This implies that she doesn't really want to talk to someone who has more brain -- she doesn't want to tell her secrets to anyone else.