KL website shows a cheap (€947) return ticket departing 12 Nov returning 19, 20, 22 Nov via AUH. As you know, EY only flies to CMB 4 times a week.
Unfortunately KL website only offers the cheaper options available (a couple of them). It could be that you can fly on EY at a higher fare on your desired dates, but that the cheapest EY fare buckets are already full.
Your travel dates are very near, so no surprise that you cannot find that many routings with very low fares. If EK is cheaper, then do EK.