They tend to misunderstand a lot of what one says Nick and it's so difficult to get them to understand what is said to them, anyway try try try again and better luck next time.
That is why you may say do you understand before moving on to the next sentence, and remember it works both ways too
I find that they say they understand because they don't want you to know they don't understand because they would feel ashamed!
Look into there eyes and you know if they understood you or put it another way , they understand everything you say but are playing you along, " yes honey I do love you so much " get my drift