I can see where YCOGSH could be about both, and he's drawing a parallel between the two issues; and maybe even establishing a causal relationship. Didn't he say, talking about NJ, that they all needed a break and that he knew he was "****ing around too much and drinking too much" and losing himself in the process? I'm pretty sure he said something along those lines, especially the losing himself part, when he talked about covering "The Wind Cries Mary". If memory serves and that's correct, then I don't think it's a huge leap to think he may have been experiencing the same symptoms and maybe that's why he pulled out to go to rehab in 2011. And if that's true, it could also be one reason why he argued for a longer break, and may ultimately have had something to do with why he left the tour so abruptly. Maybe he saw it coming. That's a lot of "if"s and "maybe"s, I know; but I don't think any of them are unreasonable assumptions. Feel free to disagree.

And yes, Bernie wrote the lyrics for WTS alone and Richie wrote the music to suit the lyric. But iirc, Richie also said that the lyric was written after he and Bernie had met for dinner a couple times and discussed life and circumstances. Richie talked about it one of the interviews he did around the time AOTL was released. It may have been the one he did with American Songwriter. I seem to remember that being one of more of the in-depth interviews that he did. Right now, I can't remember the exact words, but seems like there was something in the way Richie talked about it that made me assume Bernie had written the lyrics from Richie's perspective, based on stuff Richie had said in those conversations.

My memory is fuzzy on the details. I'll see if I can find the interviews.

EDIT TO ADD: Found them. It was easier than I thought. But this is long enough I'll post them separately.