Nancy having sex with Steve while Barb dies = El listening to Mike say I love you while Max dies
The parallels are loose but compelling 🤨
Two friends, one who is there to guard and protect the other
One girl gets distracted by a boy's cliche bullshit
Barb accuses Nancy of acting out of character, Mike is saying things that don't line up with how his character has acted previously.
Both El and Nancy are on the receiving end of some weird piggybacked emotions from someone else always in the line of sight of their love interest (see part 1 of these Nancy parallels for more on this).
Nancy almost heard Barb call for her, looking away from Steve for a moment. And El does look at Max struggling while Mike talks to her. Steve says something complimentary, which ultimately feels gross because of what's going on with Barb just 20 feet away in the UD, and Mike says a lot of complimentary things that ultimately feel gross and jarring because of everything else going on at the same time.
Both scenes are juxtaposed with horrific violence. With Nancy and Steve, it's more obvious as Barb struggling and screaming is intercut throughout Nancy and Steve kissing. With Mike and El, it's more subtle: the violence is at the beginning and at the end of Mike's speech like bookends. The message is the same though: this was not the right place, not the right time. Mike and Steve distracting El and Nancy is what led to some of the bad end results too: Barb felt neglected and went to bleed by the pool, attracting the Demogorgan. El was distracted by Mike only saying "I love you" now of all times and didn't get the reassurance she needed to save Max in time.
Of course, El is able to ultimately bring Max back to life while Nancy was unable to do that for Barb, but I think what we see in s2 from Nancy and in the epilogue from 4x09 from El is stemming from a lot of the same feelings.
Nancy and El separate themselves to mourn, looking at a reminder of the friend they lost, feeling not just grief but guilt too, even though of course it wasn't their fault.
But I think we already see and will continue to see a big difference in how they handle their relationships with Steve and Mike. Nancy buried her guilt and pretended like everything was okay. This led to a lot of simmering resentment and blaming not just herself but also Steve for Barb's death. I'm not sure on what level she was aware of this, but she wasn't in love with Steve but pretended like she was, until it led to a blowout fight and cheating.
El isn't pretending like everything is okay. She isn't talking to Mike much and hasn't returned to feeling lovey dovey even though Mike thinks he did his part in saying that he loves her. I hope we'll see more of what's going on in El's head asap in s5, as far as what she thinks of Mike's speech, if she blames him and herself like Nancy did, and what actions she's going to take from here. From previous analysis, I believe that El will understand that she doesn't need Mike as much as she thought now that she has Hopper back, and that will make it much easier to let him go romantically.
Some Nancy-Byler parallels all kind of loosely connected: part 1, part 2, part 3
