Unfortunately, there's no sure fire way to know that someone has unfollowed you on Snapchat - although there are some in-app tricks you can try out to get a clue.
If you were previously friends, and you suspect that they've unfriended you, try searching for their name in your contacts.
If it no longer shows up (and it did before), then this means you have been unfriended.
Other ways to find out if someone has unfollowed you on Snapchat include the well-known "snap and chat" trick.
Basically, you send a Snapchat message to someone - and then next time you see them, you make reference to the message you sent.
If they've unfriended you, they won't have received the message at all, and therefore won't have a clue what you're talking about!
To be honest though, if someone unfriends you on Snapchat, then they're probably not worth worrying about too much.
There are over 30 million users on Snapchat today. I'm sure you can find someone else to message!
