We're all assuming Supes comes back during JL, but could he make his return before that? WW's modern day bookends, maybe?
Sure. I'm going to be wordy, but you can literally accomplish everything below in a one-minute montage.
The way I see it is that the past-WW story has to include love blossoming with Steve Trevor... but it also has to tragically end. Given the tone of this world, I just don't see them transporting Trevor into the future or Diana macking on one of Trevor's descendants because he's a clone of Steve. It will be bittersweet and something that marks and haunts Diana in a worthy way.
Diana is living in man's world in a detached manner, but even from a distance she can't ignore the Black Zero Event. She isn't anywhere near it, but she travels to Metropolis to measure the Man of Steel to see if he's an Ares in the making. You see the seasoned Diana shadow Lois or Superman... but catches them together as Lois and Clark, being intimate and recalling Diana's own affair with Steve... and suddenly she completely empathizes with Superman and lets him be for as long as this brief happiness will last.
Something something ties into why she's looking into Lex Luthor in BvS...
...then in the end of BvS, it explains Diana's recognition and sympathy to Lois despite us never having seen them together before (that said, you can explain this by Lois's public support of Superman too).