The model spilled with Demi Lovato on the latter's '4D' podcast this week, addressing what she called a persistent narrative about them as a couple ... and one consistent theme she seems to notice time and again is that Justin supposedly isn't nice to her, or mistreats her.

It's BS ... so says Hailey, who tells Demi the best way to combat those types of phony POVs from fans online and elsewhere is to simply know the truth -- which she says she does.

That truth ... is the complete and utter opposite of what folks might speculate. She says JB makes her feel special each and every day, and that he's incredibly respectful. HB also says everyone around them knows that to be true as well, and that they have to remind each other of this fact ... because apparently, the outside noise can get to both of them.

Hailey isn't making this up BTW -- people are constantly taking clips and moments of her and Justin together out of context, and running wild with theories on what it may or may not mean. One recent example of that was during the VMA's last week, when JB won an award ... and didn't appear to hug Hailey on his way up. Some took that as a shady move.

Of course, he shouted her out on stage while accepting ... so this is just one of many moments where folks connect dots that aren't there. Another happened earlier this summer.

A viral TikTok clip showed Justin walking through a Vegas hotel following a show, and you can see him animatedly talking to Hailey. Some twisted that into him "yelling" at her -- but as Hailey is suggesting here, that's complete nonsense. Eyewitnesses say he was simply hyped.