In Chapter 3, why do you think Ponyboy and Cherry told each other things they never told anyone else before?please, i need help !!! :(

Of course, we cannot know for sure why Pony and Cherry
tell each other these things.  But my feeling is it is because they are not really part
of the same social circle.  They can tell each other "secrets" and assume that the other
person will never tell anyone who matters.

Cherry, for
example, will also not have to worry about hanging out with Pony and having Pony know
her secrets.  It's like a one time thing -- they're meeting, talking, but not having to
deal with how things will be in a long term relationship.  Pony won't have to worry
about what Cherry thinks of him now that she knows this stuff -- they'll essentially
never interact again.