I think it would be really funny devastating if the radiostatic flashback scene we saw was extremely skewed and not accurate at all. like that that is just how vox has grown or chosen to recollect it. like yes he probably did propose a partnership and alastor did turn him down. but what if he wasn't so uwu and friendly about it and alastor wasn't as horrible about rejecting him? what if vox was giving off way more predatory vibes than what we see, which would align more closely with how he was in life, and alastor could smell the danger in the air?
if vox has been obsessing over this interaction for nearly 70 years, he's bound to have started painting it in whatever way makes it easiest for him to handle, especially if he truly did care about alastor and was broken by their split. it's easier to see himself as the innocent party, the one who did nothing wrong, easier to see alastor as the one soley responsible for the pain he felt. I'm sure alastor wasn't "nice" about it, but it's obvious that he cared for vox in his own way and while he was always going to reject him, he does not seem to get pleasure by being overtly cruel to those he might consider friends, so his actions seem completely overblown. almost like when you've been ruminating on something over and over and just making it worse and worse and worse in your head.
and coming to this line, the one that doesn't really seem to match up with vox's behaviors we've seen, and alastor just looks so ... sad when he says it. vox being in denial and making excuses and lying to himself about how he got where he is, blaming everyone but himself for the pain he feels? I think that would be an insane route to take for a vox redemption arc but so incredibly plausible.