If the X-Men have to treat everyone on the team according to their past, and never forget, half of them will have to kill each other first while their enemies sit and rejoice and wait to reap the rewards.
Besides, Scott wasn't thinking very straight at the time he got involved with Emma cause of the whole Apocalypse-took-over thing, and he wasn't particularly emotionally connected with Jean as before.
And Emma is a better girlfriend for Scott than Jean imo. Semma > Jott. I don't mind if she had caused Jean gone insane, some people are just ferocious when it comes to get rid of the rivalry, and Emma is hardly the girl-next-door type anyway.
I suppose I'm a little biased cause Jean has not much of place in my mind at the moment. *shrug*