Mechanically, they are responsible, OTP and all that.
Someone suggested bringing back the O5. Well, you can't have Jean Grey simultaneously existing and not tied to Cyclops even today, in these relatively modern times, so just imagine 40 years ago. So the question became, "how do we get rid of the current love interest so Cyclops can have a different love interest?"
We should ask ourselves if Jean is truly genetically superior to Emma since both Jean and Jean's clone died from this question, but Emma has survived it unscathed lolol