She Liked it.
Without strife, your victory has no meaning.
Without strife, you do not advance.
Without strife, there is only stagnation.

This message has been deleted.

Jenny’s father likely threatened to hurt her if she opened her mouth about what went on. Pedophiles are known to do that as they empower their victims.
My password is password

The only poster who made Steve Lake wet his pants 4 times without ever breaking a sweat each of those times.
Wildmanwizard

It's something you want to broadcast in an online message board instead.

It's embarrassing to be sexually abused by a relative it's not something you always want to tell people especially when you're young.
My password is password

It’s normal for victims at Jenny’s age to not want to open up about the sexual predator, especially if it’s a family member raping them. Jenny likely didn’t want her only friend to get the wrong idea, branding her as a slut. Forrest was the escape rock she went to for comfort.
My password is password

Forrest says (referring to Jenny's father), "He was a very loving man. He was always kissing and touching her and her sisters."

She has sisters?

This message has been deleted.

This message has been deleted.

Yeah, it seems like Jenny only has Forrest to turn to when she's older, even though she has at least two sisters.

I did notice that, which makes me question whether the relationship with her sisters was strained or not. The fact that Jenny didn’t even turn to them while she was severely damaged hints this. Forrest also never tries to contact them about Jenny when he grows up and his letters are returned.
I’m curious to know how they turned out, even if they were only mentioned.
“There are no atheists in foxholes, eh?”-Keith Jennings from the Omen.

Did you notice Jenny's sisters are left behind to continue being molested by their father? When she moves in with her grandmother, her sisters are nowhere to be found.
They're not even mentioned at all later in the movie. Were they at the wedding?