Sometimes it is easier to talk with an adult figure -- usually male/male and female/female -- who is not your parent, especially, IMO, if you are a teenager. Let's assume that GG had a good relationship with his step-dad, but maybe JW and GG had more in common, similar interests, or that JW simply took the time to pay attention to him about things that were not wrestling.
I had a close talking relationship with the mother of a close friend of mine. She & my mother were good friends, too, and we were neighbors. We'd just drink coffee and joke, and chat, etc. No secrets from my mom, with whom I was also very close, but my friend's mom was about 10 years younger, and a bit more "with it." I still miss her today, and it's been a long, long time.
I don't think this type thing is that uncommon -- at least with females. IDK about males, but I don't see anything wrong with it ("on paper" in this instance, certainly), and prolly both GG and JW enjoyed each other's company. Teens, especially, don't necessarily share some of their doubts, questions, plans, etc. with their parents even though things are fine between them. It was just that this relationship turned out to be such a ..... betrayal. On purpose or not? Who knoze? I'm not sure that I'm willing to give GG that much credit. JMHO.