$(document).ready(function() {
  $("a.load_reviews").on("click", function(e){
 //Send AJAX LOW-LEVEL get request
    $.ajax({
      method: "GET",
      url: this.href
    }).done(function(response) {
 //get response
      $("div.reviews").html(response)
 //Load data into html
    });

    e.preventDefault();
  })
})

$(document).ready(function() {
  $("a.load_reviews").on("click", function(e){
    e.preventDefault();
 //Send AJAX LOW-LEVEL get request
    $.ajax({
      method: "GET",
      url: this.href
    }).done(function(response) {
 //get response
      $("div.reviews").html(response)
 //Load data into html
    });      
  });
});

move e.preventDefault(); up top