I just can't buy into Wishtash feeling much heartache for Neveah going away. Not even as something that used to belong to him. It's not about whether they had a bad time living together, in fact, the guy spent so much effort into not living in his own home, the two barely interacted together.
I can buy that, now that he's not tiptoeing around his own house trying to avoid her, he's found all her old possessions, and since they now show that she had been one-sidedly pining for him, he'd be feeling guilty that he neglected her for ten years without giving her a chance to listen to her story. I can also buy that maybe his self-image as a "good guy" is crumbling and now he feels threatened because of the harsh reality that he's a douche, maybe that part plays into wanting Neveah to remain under his thumb so he can pretend to show her kindness when he only showed her avoidance before?
I can't really buy a heartbreak, though. It's a different story if they even interacted, but nothing is really shown here to trigger good memories.