Blue

Yes indeed! How about Steve Douglas' oldest son, Mike on "My Three Sons." After the CBS color episode debut where he and Sally were married, they were never talked about or heard from again.
Ya know, about Blue "warming up" to Victoria; every time I watch the early episodes, I get the impression that Blue may have felt somewhat foolish, or maybe a little ashamed that he had given both her and John so much grief at first. From what Mark Slade put into the character at that time, that's what I see coming out. Of course, I could be completely wrong too. But I thought that they made him get over his ill feelings rather quickly. In fact, I felt worse for her because of the way that John treated her at the beginning. He was TERRIBLE with her!

According to the excellent, comprehensive official High Chaparral web site and the newsletter, it sounds like a case of he said (Mark Slade) and he said (David Dortort). According to Mr. Slade, he had quit HC because he was not allowed permission to take three weeks off to make a movie which he was also a producer of. He states that Mr. Dortort did not even give him the decision personally, but had a staffer do it instead. To add insult to injury, only two of the HC cast and crew empathized with him: Cameron Mitchell and Linda Cristal.
Slade also offers that he did not want to be typecast forever as a "Blue" type character and had to think about the future.

Mr Dortort states that it was simply a matter of Mr. Slade asking for a raise that could not be given due to budget constraints, and Slade getting the wrong advice to hold out until he got the extra money. By the time Slade decided to give up on the raise, it was too late. Production on HC had already began (and probably the new character of Wind), and Slade was shut out.

The only thing that Mr. Slade and Mr. Dortort seem to concur with is that Slade would have liked to return to HC in the future, and Dortort wanted to bring him back for the 5th season. Unfortunately, the show got canceled after the 4th season (I know that Bonanza had higher ratings and a larger following, but HC, in my opinion, was a superior western in every way).

I thought that Mark Slade was excellent as Blue, although Blue seemed a bit too naive at times. However, if Cameron Mitchell or Henry Darrow would have left HC, the show might have ended right there.