I wrote a
long Tumblr post about it last year, including examples from comics.
Marvel has a very long history of treating Lorna like she exists to be Havok's girlfriend. Every time they're written as a couple, Marvel rips away core facets of Lorna's identity to make her fit that mold.
First time they were a couple, Lorna lost her feminist nature, Jean as her best friend, Iceman as a close friend and potential love interest (Sina Grace only used her as a throwaway cell phone message), and her status as second woman to join the X-Men meaning anything. All of that got stripped from her to make her Havok's clingy girlfriend who gets repeatedly victimized for the benefit of everyone that isn't her. It got so bad that by the late 90s, when Havok appeared to die, writers wrote her locking herself away in an apartment crying and obsessing over his uniform.
Then she got brought on to Genosha. Without Havok, Magneto was restored as her father, she got Wanda and Pietro as siblings, she had actual character development with Genosha (genocide, people revering her, how she handles the trauma, etc), she played a meaningful role in House of M. After nearly 30 years stuck mainly as Havok's girlfriend, the first time she got to be not that, she made progress.
Then she got forced with Havok again, to go into space. In that time, she lost her Genosha history (Marvel acts like she has no stake in it at all), she lost getting to be part of major X-Men and Marvel events, she lost the darker edge to her personality. The second she's with him, she loses huge chunks of development yet again.
Then Havok broke up with her. And already, in the very story that launched the breakup, Lorna finally got her origin story told after 43 years without one (decades after Havok got his). She then got to lead her own team on All-New X-Factor. Spend time with Wanda and Pietro again. And Luna. Had a bit of flirt with Gambit, too, that could've gone places if it lasted longer.
And now we get to the present. After two years of Lorna in forced limbo, they brought her back mainly to be a supporting character for Havok's story on Blue, with a bit of Magneto handled the same way. X-Men Blue #9, presented as the big return for Lorna, ends up being all about how she can "save" Havok as his Manic Pixie Dream Ex-Girlfriend, with a bit of "watch out for Magneto's Daughter (TM)" thrown in. Lorna's supposed to be a mentor to the Blue team, but that makes up only one page out of 30 something issues. Malice is brought back, but because the 5-issue story arc is mainly about Havok, it's in and out with no depth whatsoever.
That's how Havok is toxic for Lorna. Every time he's used anywhere near her, a part of her character and her potential dies just so he can have a hot green-haired (ex)girlfriend to boost his profile and feed his stories.
Every time she's free of him, she gets to actually be someone for a change. She gets to have friends, take part in events, figure out who she is and what she believes. Things that should've happened decades ago get to finally happen.
I don't think it's absolutely impossible for Lorna to ever have a relationship with Havok that isn't toxic. However, such a thing is going to take at least 10 years of the two kept apart with Lorna actually used as her own character. Marvel needs to recognize internally that Lorna is a good character worthy of use and respect in her own right. Only then will any relationship between them have a shot at not sucking.