Q: iphone not sending imessages/text messages

Hi there everyone I am wondering what my issue may be?

I am able to receive my fiance's text messages (I think most of them at least) but I am not able to send him an imessage/text message to his iphone.

It doesn't even show as delivered for some reason and he keeps saying HELLO???? So i am sure he is not receiving them although they look as though they have been sent but it still doesn't show as delivered. I tried to message him off of my iPad Pro just now as well on wifi, signed in with the same apple ID my iphone has and on the iPad it is showing as "not delivered". At least on the iPad it shows as Not Delivered, but on my iphone it just shows my message with nothing under it, no delivered, no read, no nothing. Does anyone know why this might be? I also turned off the imessage thing on my ipad settings where it shares between iphone and ipad to see if that will work, and it still shows as not delivered on the iPad Pro. So far it seems like it is not my cellular provider Sprint since it is not able to send on the iPad Pro either.

HALP!