You told your business partner you were going to send him to jail and then went hunting with him?
You went back to the town where your baby's father had a new imperious wife and asked him for your old job back? I think I have this right, my kindle keeps skipping so maybe I missed that she didn't know he was married or what his wife was like.
You never asked if the baby was yours? Maybe I missed on that, too.
The first scenario: simply stupid.
Rachel never left town. It's a tiny community, and if she'd been with anyone else it would likely be known about. Also, George is shown comparing a photo of himself as a baby - at least I assumed that's what it was, although the album was kept in the office?? - with the photo of (Rachel and) Jacob; I believe it's then that he puts the money in the envelope for them, seemingly convinced of his paternity. Hardly DNA matching, but as a dramatic device its message seems clear: Jacob is George's son.
I think that, in his own way, George was being a "gentleman" by not asking Rachel outright about Jacob's paternity.
It's the Great Depression. Rachel's father, her only means of support other than herself, is dead, killed by George - in the book/a deleted scene, after he, armed with a knife, had confronted George in the street about Rachel's pregnancy - and she has a child to care for. What other kind of work is there for a woman in a lumber camp? Even then, it's someone else who approaches George, on her behalf, about her getting her job back.
I don't think that Serena's imperiousness - good word, "imperious!" - matters to or registers with Rachel. A(nother) deleted scene shows her in awe of a telephone, afraid to speak into it; I got the impression that she's what would then have been called "backward." (Someone who read the book could help me out here.) Not George's equal intellectually, and not worldly enough to recognize the danger posed by Serena.