JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test">Test 0</div>
<div class="test">Test 1</div>
<div class="break">Break 0</div>
<div class="test">Test 2</div>
<div class="test">Test 3</div>
<div class="break">Break 1</div>
<div class="test">Test 4</div>
<div class="test">Test 5</div>
<div class="test">Test 6</div>

CSS

.group{background:red; margin:10px;}

JavaScript

$("div.test").each(function(){
if(!$(this).nextAll(".break").length)
$(".test").last().after('<div class="break">Add last break element</div>');
if(!$(this).parents(".group").length)
$(this).add($(this).nextUntil('.break+.test').andSelf()).wrapAll('<div class="group" />');


});