Maybe so, maybe no. ;) Sometimes it's hard to tell.

I think the split in his brotherhood with Jon occurred far earlier.
We just finished the 2011 tour on our touring website (for those who are interested: https://bjtours.jimdo.com/let-s-go-o...bon-jovi-live/).

If you remember that tour, it was the first time that Richie had to be replaced on tour shows (beforehand it happened only once in Puerto Rico 2007).
During the 22 US shows with Richie he was allowed to sing a song in 21 of them.
When he was back for the European tour he was once allowed to sing a song...in 24 shows.

So I think those were the first cracks to be shown but couldn't be recognized by us because the rest of the masquerade was still too perfect.

When they started the Because We Can tour in 2013 he didn't sang at all during the 20 shows he played with them. Although he had just finished his solo tour and seemed to be in much better shape than Jon at that time...I remember discussions back then about Jon being sick or having other problems because he barely moved and sweated as hell after only 3 songs being played.
And like Tictoc already said, Richie looked healthy and focused in his playing.

So with all this stuff we know nowadays in mind I think back in 2011 it all started to go bad between Richie and Jon which finally escalated in his departure midtour in 2013.
Drugs and booze most probably were the reason for the start of their dispute but I don't think it was the reason for Richie leaving the band.

Richie once was quoted that the Stones wouldn't tour without Keith Richards. I don't know when exactly he said that, I think it was sometime around his departure...but maybe he thought that Jon wouldn't tour without him either and didn't show up to make a point. But unfortunately Jon made his point by going on without him.
I know, it's pure speculation, but to me that's the story that makes sense the most.

Are you sure about that? Setlist.fm has him singing I'll be there for you at his last show at Lubbock Texas.

Yeah, you got me! But Lubbock was the only one.

I mean it stands to reason that him not being allowed to sing a song as a reason for his departure that him singing one and then splitting doesn't make a ton of sense.

My point isn't that singing a song or not made him leave.
But that this might be a indication of how his relationship to Jon has changed after his rehab in 2011.
Even with him singing There 4 You in Lubbock makes it 1 in 20 which is quite a difference to 21 in 22 back in 2011.
Or if you'd like to go even further, in 2010 he sang in 81 of 83 shows.

I guess, yeah. In the North American legs Richie singing was a major pee/drink break. They'd give him a solo song or an album cut and then as the tour went on switch him to a band hit and even then it just didn't keep attention. It's possible they changed it up that tour because they were throwing six, seven songs off an unreleased album into the set, and then to have Jon not be on stage.....I kind of get it if that's the case.

Richie made the Jagger comment long after he left. It was sometime in 2014, I'm pretty sure. I still don't believe he thought Jon would stop the tour, bc he surely knows Jon better than that. I think that was a reaction to Jon's ultimatum that he tour or leave the band.

I didn't realize that Richie only sang once in the EU shows in 2011. But Richie and Jon both said, in 2012, that Richie would be promoting AOTL while they toured. Given the dispute they allegedly had over whether it was too soon to tour, I've wondered if one of the concessions Jon may have made was that Richie could still promote AOTL on the BWC tour, and if that was one of the reasons Richie agreed (other than not wanting to lose his place in the band). I know those three songs were included in the deluxe edition. But then that didn't happen. Lubbock was the only show where Richie sang a solo (which was IBTFY, not Every Road or another song from AOTL) and that was the last show Richie did with the band.

So while the number of solo spots may have been an issue;, I would guess that the bigger part was not being given an opportunity to promote Aftermath as promised. I don't know how much that may have influenced his decision; but I think it may have been a part of it.

I see your point but I don't agree with it.
Yes, especially in the US people used his song for a pee/drink break.
But that didn't seem to matter for quite a long time.
Since it's pure speculation we won't solve that matter.
But I still find it quite remarkable that after his missed shows in 2011 he only sang in 2 of 47 shows while before it was in 200 of 204 shows.

Richie singing a song:
Lost Highway Tour: 98 / 99
The Circle Tour: 81 / 83
Live 2011 before rehab: 21 / 22
Live 2011 after rehab: 1 / 24
Because We Can Tour: 1 / 23

Like I said before, my point isn't that his solo spot made him leave but that it indicates a change in his relationship with Jon ;)