Make sure iMessage is going through I have read so many different answers and really just need a truthful answer. 

My ex-boyfriend and I both have iPhones.  I been trying to send him messages but it doesn’t say 'Delivered'. It doesn't display anything at all. 

I was told first that if blocked it would immediately say Delivered because the person blocking doesn’t want you to know you are blocked. I've also been told his phone is off or on DND. 

Is there a way around it to text and be sure it goes through?
It's impossible to say what's happening with your phone since we don't know what your boyfriend did or didn't do with the messages. Without knowing if he actually receives the messages, we can't say what the exact problem is. He could very well be lying to you about the messages. I would send him a text while looking at his phone and see what happens.