Definitely there was a falling out with JD.
Lobsterboy got tired of being Beta Male to JD's Alpha male all the time I think. I remember towards the end they were struggling to even be civil to one another. (I remember a couple of screaming matches - and they weren't fake. One was about I think the astronaughts who died on Columbia and JD said they were heros and Craigie (Lobsterboy) disagreed and they got into it. Another was when JD had just gotten married and was lecturing Craigie about marriage and how if his (JD's) wife ever fucked around on him the marriage would be over. Craigie (rightfully) said something like "so you've been married for 6 months and you're an expert" (Craigie having been married for 10 or more years.
Anyway, Craigie was definitely outgrowing the golly shucks side kick role and JD had / has a massive ego and he would go out of his way to make sure Craigie KNEW he was second fiddle.
When they brough Ryan on board - who was just an intern, Craigie could see the writing on the wall. Ryan was only too happy to suck JD's cock and that's exactly the kind of second mic that JD wanted. Finally, Craigie jumped the shark when JD orchestrated this boxing match between Ryan and Craigie. Craigie wanted nothing to do with it, but JD forced the issue and goaded Craigie into it. Finally, they had the boxing match and Craigie lost. I knew right then it was over. Shortly thereafter Craigie just disappeared.
I believe Craigie is in Windsor now in a smaller market, but running his own morning show.
Since JD has been in the morning show on Q, he's gone through quite a few Beta Males.
First there was Craigie
Then Ross Mcleod (if I remember correctly - who was every bit as smart as JD (so you knew that wasn't going to last)
Then there was Bill Hayes - JD's brother - who moved on, as opposed to being pushed (though I could be wrong)
And now there is Ryan. Ryan seems to be content to be the goofy side kick for now, and frankly he's good in the role. But sooner or later, I gotta believe he's going to grow tired of it.