It's sad, but some people just don't know how to be honest about things like that, especially if it's nothing you've done.
Honestly, even though I would want to do the right thing, the thought of actually saying something like that even in theory (and I have said it once irl) makes me uncomfortable and hot and cold. No one wants to hurt someone else.
If it were me I would guess 'they're just not that into you/me' it's probably not personal. It's a shame they aren't treating you with dignity and consideration though, it's the least you deserve.