I see no reason why he and Maggie wouldn't get back together.
Joel wanted off the show, think KLS wrote about that in Scrapbook Memories. I personally couldn't see anyone other then Joel playing Joe, but I think they should have killed him off instead of what they did do to get him off the show. Just don't see what happened actually happening, he was too strong for that.
In
Scrapbook Memories, all I recall her saying is that she and Joel were very close and that he, along with Alexandra and Mitch Ryan, had left the show. But I can't remember that she stated in any other publication that he wanted to leave. I also don't recall that he ever said it; only that he had become unhappy with the way his character was written but was willing to take on a more challenging role. My understanding is that the decision to write Joe out of the show was a creative one-- they had nowhere to go with him at the time, and since there wasn't another character for Joel to play, he moved on. He was quoted in the fanzine "The Eagle Hill Sentinel" from 1969:
... Alexander Moltke had left at the end of the previous storyline, and early into this one, Joel Crothers announced he was taking a part on the daytime series Secret Storm. "Joe Haskell had been made into too colorless a character," he complained. He would have relished the role of Quentin, but was told he had "too honest a face." So Joe was taken away to Wyndclliffe, never to be seen again, and his girlfriend Maggie Evans, once a hard-bitten girl from a poor family, became the helpless victim-in-residence. ...