Tbf hosts are often really shady and tbh Shinya hasn't exactly been the most well adjusted...

Tbf hosts are often really shady and tbh Shinya hasn't exactly been the most well adjusted individual or made himself look particularly trustworthy outside of the home bit, so it's not that strange that Ginji's words made Haru start doubting. I mean, in the grand scheme of things Haru doesn't know either of them that well. I will say that between one single host and a warm family who took care of the cat you couldn't, I know who I would trust more. But at the same time Ginji is also Mel's fave, so that's bound to add some weight too, and Haru's experience with getting abandoned is probably making him want to cut things off before there's even a chance he could get hurt further, so he can't see the bigger picture.
If Haru cooled down a little he could have tried to gather more information before doing anything drastic, but he's just a young an emotionally inexperienced guy who knows the dark sides of the world he's in.
Ultimately Shinya and Haru both kinda suck at communicating and both act reactively in different ways. They never talked about boundaries or what their jobs mean to them. They're both young, emotionally inexperienced people in a harsh adult world full of exploitation.
This was a pretty painful chapter :( But I hope it leads to them actually talking