BvS and ZSJL imply Lois was pregnant when she died at the batcave in a future timeline, giving an intense grief to Clark that made him unable to resist to the Anti-Life equation and then he became a slave of Darkseid.
(The Anti-Life equation was a transcendental mathematical formula originally said to allow those who knew it to dominate the will of any sentient race; this is the ultimate goal of Darkseid).
BvS is on the board for Stranger Things 4 and if the theory of "Will Byers being the Superman that landed on Mike's doorstep" is correct, then Mike "dying" after Will learns that his feelings are reciprocated would make him more susceptible to Henry's plans of controlling him.
Will even said it: "without heart, we fall apart".
In the films, Lois was the key to Superman's heart because she was his world.
In Stranger Things, Mike is the key to Will because he's his heart and he always will be.