About Josy.
I think you're going a bit too far on her reaction to a break-up. In episode 4, the MC almost made a declaration of love to them, then the relationship between them and the MC in the trouple goes ideally well, only for him to dump them in episode 9. That she's hurt and sad is perfectly normal given how the story sells her attachment to the MC from the start.
I expected more problems with multiple relationships with the main girls. Remember, though, that Bella dumps the MC when she finds Cathy's panties. At the time I took it as a warning to the player to be careful what you do with the LIs. In the end, not much negative happens if you've played Don Juan with the LIs (a quickly dispatched little quarrel between Bella and Jill in episode 9, and Josy hurt and sad in episode 10). I think we're doing well, I expected worse and maybe it will happen.
As for Josy's attitude if you spend the evening with her, yes, she goes all out, but she only does so if the MC has given her a glimmer of hope in episode 9. Here I feel that DPC has trapped us a little in episode 9 because the answers to be given to Josy are written in such a way that the player chooses to leave her a little hope rather than close the door for good. The answer that's supposed to close the door is "the two of us would never have worked out anyway". I find this unnecessarily mean-spirited on the part of the MC, it's not like him, and it influenced me to choose the less mean-spirited option of leaving the door open for Josy.