Telling Lois that he's Superman is a big deal.
She seems to know by the end of the movie. But it doesn't look like their romance is the dramatic center of the movie. So she probably already knows from the beginning.
It is a big deal, and I think... that's why J.G. is not going to deal with it here. It would be retreading old ground from the original 1970/80 films, the Henry Cavill Superman era, the Lois & Clark and Smallville TV shows, not to mention decades of comics. Better just to move beyond that point.
I THINK in all iterations of Superman, the big secret identity is closely tied to their romantic relationship. Either Clark and Lois were (becoming) a couple, and THEN he reveals his identity, or Superman and Lois were (becoming) a couple, and THEN he reveals his identity.