... with the current version of snapchat, how long after you stop interacting with someone do you stay 'best friends' without blocking or deleting them??

dose it happen slowly by itself?
for example, if i have 2 best friends (showing the little smley face) and i stop interacting with one of them completely what will happen to the emoji? will it change over time, suddenly or stay the same?

if the emoji is still there 3 weeks later what dose that mean?
is it based around frequency or will one interaction over 3 weeks keep them as a 'best friend'?

any real and swift info on this would be amazing, and remember im not asking about blocking ect. just what snapchat does automatically over time, and i need a correct answer please not a theory. thanks