Why do I keep getting "retry"?

[AC Question]

My LG G4 phone has only recently started doing this, and only to two people who live in the same house (which may matter based on location). Whenever I send texts to these people from my phone (especially ones of more than 100 characters or so) it tells me that the message failed to send and prompts me with a "retry button in the text bubble of the failed message. I hit retry and it attempts to send, sometimes it doesnt tell me it failed again and sometimes it won't ever tell me that it successfully sent, i'll just keep getting a "retry" button. However, sometimes my messages do send, and every time I hit "retry" it send them again. The problem is: I have no way of knowing whether they sent or not unless I ask them if it went through, so sometimes i'll end up sending the same message up to 5 times because of it telling me it is failing to send. Sorry the description was kind of long but if anyone can help i'd appreciate it.

 

[Tim1954]

The longer messages get converted into mms these days i think.. can you send pics via mms just to see if it's enabled...