I wanted this to be it's own response due to it being kind of heavy.
No spoilers as we intend on revealing what went down but neither were "in the right" in the deterioration of that relationship.
I'm putting the rest in spoilers as it's going to be a deep dive into Jean's psychology that may ruin some people's boners for her.
Jean has image issues and a desperate need for control. While she becomes self aware of it, her initial interest in Null is outright predatory. She's a senior 1 school year away from graduation and is put in charge of training with/tutoring a freshman. While Null is an adult and able to consent, there's still a power dynamic there that is kinda squicky.
Whether you activate her quirk, which enables a really unhealthy coping mechanism, or not she'll still be moving into a teaching position and wanting to continue a sexual relationship with Null.
Laura is developmentally stunted and Rogue has had all of her self confidence beaten into the dirt. Though both are still gonna be students of equal social standing and Laura is socially educated enough through her storyline to be fully aware of what she's consenting to in entering a relationship with Null.
The best defense Jean can come up with is that she has gifted child syndrome. On top of that if you don't date Jean she will become increasingly possessive of Null and if you activate her quirk and opt out of dating her she can become combative with other girls.
Y'all can see a preview of this in an interaction between her and Rogue.
While we do have Jean address his behavior, it's gonna get worse before it gets better. She's a flawed individual and Scott has just as much reason to be annoyed with her as she does to be annoyed with him.
If your boner has yet to be killed for reading the above I'd advise not reading this final paragraph if you're still only in this for the horny.
Scott's ego comes from the fact that he has the responsibility of leading people into life or death situations against tangible threats. Jean's ego stems from her being Xavier's "special." Null is the new "special" which is a driving force for why Jean thinks she "deserves" him as a romantic partner.
For those who have opted to read the above. Jean is not a bad person. She will have an arc that expands as the game develops because as we've promised multiple times, the girls will continue to grow as people and characters even as the cast grows larger.
That's a positive of the X-Men. Despite being a large ensemble, good writers managed to balance them so each had their own arc. As many of you have stated in comments and reviews, we have good writers.