sprint galaxy s8 converts sms to mms after 160 characters

[Android Central Question]

Hello!
My Sprint Galaxy S8 has been doing this for about a week now, very frustrating stuff. I use the stock messaging app. Everytime I'm texting now, when I go over 160 characters it turns the message from SMS to MMS. I usually wouldn't have a problem with this, but my girlfriend has data caps, and when she goes over data, she cant recieve my texts when they're sent mms. I used to be able to send about 7 text blocks before it would convert to mms, and now even if the message is 161 characters it will be sent as mms. Please help me. I've been trying to find a solution all night and nothing so far has lead to a solution.

 

[B. Diddy]

Welcome to Android Central! That's strange, because 160 characters is the single message limit for SMS, so it should automatically change to MMS with character 161.

Is there an option in the Messaging app's settings that allows you to break up a long message into separate SMS messages?