I agree that Scott's character changed. I don't accept that makes him somehow incompatible with Jean. The reason why is that you're partially mis-characterizing who Jean is. Yes, her first instinct is to take a diplomatic approach. If you think that's the only round she has in the chamber you're very wrong. When push comes to shove there's this Jean too:
or for something more recent...
Jean didn't have to live through Decimation\Utopia\M-Pox. If she had I would suggest she would have fought just as hard as Scott to see mutants survive. I agree that her first instinct is to find a peaceful means of protecting her people but in many cases Scott didn't have that choice and neither would Jean have. As for sacrifice, Jean is just as familiar with that as Scott is. She's lost everything twice over for the X-Men.
I also disagree that Scott's development couldn't have been done while he was with Jean. There are those who believe it, yourself included, but no proof of this claim is ever offered. Yes, Scott did change, but the changes had already begun
before Jean's death. To suggest that something so radical had occurred to him that his best friend and spouse could no longer love him suggests that all his other friends were justified in turning their backs on him as well. When the X-Men did that it seemed contrived for dramatic effect. If Marvel had done that with Jean, it would have felt even more so, because at his core, Scott remained much the same man he always was.
His values didn't change, only his willingness to follow them absolutely even if it meant the death's of the few mutants left. His goals didn't change, only the methods by which those goals could be attained, and even then only by degrees. In the end, his peaceful demonstration in UXM 600 shows that Scott yearned to find peaceful solutions. Jean's presence would only have helped with that.
Scott fought a long war of attrition with his conscience and made compromises along the way. Do you really think Jean wouldn't have if she had lived through what Scott had? Maybe if she'd been around to support him, he'd have had to make less of those. The truth is that we'll never know for sure if their relationship could have survived the man he became or the woman she would have become. I would suggest though that it survived Jean's death, Scott's marriage to Maddie, and as we saw in PR5, their broken Morrison years -- all that bods well for them having made it.