Thanks for your thoughtful critique.
It is unquestionable that Richie is the novel is not gay. As a kid, he has a crush on Beverly, and as an adult, he has a pregnancy scare with his live-in girlfriend. I guess he could be bisexual, but there is no explicit evidence of his feeling romantic toward males comparable to the explicit evidence of his feeling romantic toward females. Plus Stephen King has said that he did not write Richie as a gay man.
As for the movie, you are right that Andy Muschietti and Bill Hader interpreted Richie as gay. Thus, they dropped a few hints into the movie. My point — which I didn’t argue well — is they should have made it clearer. You wrote many sentences above explaining these clues. Instead, it could have been handled with a single exchange. For example: “So, Richie, what’s new with you?” “Well, my boyfriend and I . . .” Done.
Bottom line: if a director is going to change something fundamental about a character from book to movie, there should be more of a commitment to that change. Not just a series of hints but something concrete. It’s all about representation, right? To me, a weak representation is not much better than none at all.