I have the following layout of three columns and I'm using bootstrap. When I click on a column each column next to that one gets expanded too. For some reason I cant get the snippet code to show it here so I attached an image of what I'm getting.

If possible I would like to change this behavior. I would like to click on one column and expand only that one and not the other columns. Any ideas on how I can implement that?
$('li.submenu a[href="#"]').click(
function(e) {
e.preventDefault();
$(this).toggleClass('open');
$(this).next().toggle();
$('.col-md-4').toggleClass('flex-last');
return false;
});
ul.ul_submenu {
display: none;
}
.submenu a i {
transition: ease .3s;
}
.submenu a.open i {
transform: rotate(-90deg);
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://kit.fontawesome.com/a076d05399.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container-fluid">
<div class="row">
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #1 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #1 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #1 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #1 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #2 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div class="col-md-4">
<ul>
<li class="submenu" id="atag"><a href="#">Apparel & Accessories #3 <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Clothing <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu"><a href="#">Men <i class="fas fa-caret-down" style="color: grey;"></i></a>
<ul class="ul_submenu">
<li class="submenu">blabla</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
</div>
</div>