Carol’s first husband was a survivalist. Daryl is nice for a survivor and risked his life to find her missing daughter.
She may be maintaining a friendship and equality to avoid sliding into the pattern she had as the inferior one to a dominant man, and then to abuse.
I don’t think she has any fear Daryl would turn out like her husband. Ed was not only an abuser, he was working his way up to raping his own daughter. Carol once told Daryl he did more to help Sophia than her own father ever did.
Also, as Carol recently said, she became the strong woman she always wanted to be. I don’t think she would tolerate that kind of treatment from any man.