What was Richie's big secret?

Question

In It Chapter Two, when Richie is going through the Derry alone, he visits the old arcade and the park with the Paul Bunyan statue.

When Pennywise appears, he starts teasing Richie saying that

I know your secret, your dirty, little secret!

What was this secret?

The scene in the arcade might suggest that

Richie is gay

but I find it a bit hard to believe since there was no other indication for that, other than willing to share a token to play StreetFighter with another boy (who accused him rather to show-up in front of his cousin). Also in the book, Richie was divorced and was living a life of a celebrity, full of drugs and groupies.

Answer 1

You guessed right.

The two big pieces of evidence is the token scene, which you noted, but also the very end of the movie where

Richie carves R + E into the kissing bridge, which stands for Richie + Eddie.

You're also correct in that this is a significant deviation from the book.

Answer 2

GGMG answered it pretty well but also there are official words about it. First, even in the novel, it was hinted as per producer:

Barbara Muschietti told IGN that there was one key Richie and Eddie moment from the book that stuck with her over the years: "The scene of Eddie's death, when Richie is saying goodbye, and caresses his cheek stuck with me for a good, what, 30 years. The way I interpreted it was that there was love there. I don't know if romantic, I don't know. But it feels totally natural that it would be unrequited love. To me, when Andy presented it as a possibility, it felt very natural."

But this time they didn't want to just hint it but show it to which was also the actor's demand:

Bill Hader wanted the film to commit fully to making Richie gay or to not even bring it up. "Andy and I talked about how overt we should make it, and I said if it’s not overt, then why is he in the movie?," Hader told the New York Times. "You can’t do a half measure on it. You’ve got to go the full way or don’t even allude to it. Let’s not be coy. Let’s just say what it is."