I'm going to explain the way how to actually check out who has unfriended you on Facebook as quick as possible, because... I'm at work. It's pretty easy and I was a bit skeptical at first since I haven't confirmed it. But today I tried it out on my friend's phone and it worked, so my doubt was cleared a little.
This will not need using a dumb and poorly written website that has so much annoying popups and ads. What you will need is your Facebook App and your Facebook Messenger. :) Ready?
1. Open up your Messenger app.
2. Tap your profile photo located at the top. In Android, location may vary.
3. You'll be redirected to this next screen, like so. Then, tap on My Day.
4. Tap on Everyone.