Facebook Message Sent But Not Delivered

Facebook message sent but not delivered in days? ۔

I use messaging apps and websites. Both did not message. Just sent This guy I talk to all the time is one of my best friends, so why is this happening? :( Didn't receive my message?

update

And that's all. My other friend, my message has been sent.

I could be wrong. When a message is sent, it means that what you have written has crossed the Internet and entered someone else's messaging app. It will be shown as sent when the person is using the phone, when the phone is not connected to the internet or turned off, it will be shown as sent and will not be sent. Once the person turns on the phone or connects it to Wi-Fi, it will appear as sent.

Your friend shuts down Facebook or quits.

Or a place without internet.

Facebook Message Sent But Not Delivered

Facebook message sent but not delivered in days? 3
I use messaging apps and websites. Both did not deliver the message. Just submit. This is the person I talk to all the time, he's one of my best friends, so why is this happening? :( Didn't receive my message?
update
And that's all there is to it. My other friend, my message has been sent.
I could be wrong. When a message is sent, it means that what you wrote has gone to the Internet and to someone else's messaging app. It will be shown when a person is using the phone, when the phone is not connected to the internet or is turned off, it will be shown sent and not sent. Once the person turns on their phone or connects it to Wi-Fi, it will appear sent.