Moto e wont send texts to certain number but will call and send pictures

[AC Question]

Ok so my moto g was sending messages perfectly fine this morning. And i just left my house and tried texting my boyfriend and they say sent but no delivered and when he sends me messages i dont get them. But i can call him and send pictures to him. Its only his number that i cant send texts to and its frustrating. How do i fix this?