This answer is for you. It's not about him.
I guess to answer your question properly, I would have to figure out the underlying issues.
Trust? Communication? And, belief in yourself?
Until you answer those problems, you cannot expect anyone to take you seriously.
If you don't put your trust in him to believe what you tell him is the truth, then communication is certain going to be a problem in the long run. Therefore, he will not change, because your communication efforts were weak.
Besides, if you LOVE someone, then you're never going to sit and wonder if he believes you do. Because you'll know he understands.....Love isn't something that needs explanation, because it's beyond, the average person ability. They simply feel the emotion. Not understanding the meaning.
I know this seems long, but your problem is easy.
Secondly, you're also going on the assumption that change is going to happen if you let him know that you love him. If he is too stupid and can not see by your actions(actions dictate love, not words), then he is worth your effort.
I hope this helped.