Thanks for the new chapter!
I have to say Ichinose should think that even if he continues to ignore Hanabi, she will continue to pester him and target people around him. Dating Yukishiro or not will make her a target again, sooner or later so I think Yukishiro saying as long as she is with him, she will be alright is quite true. And if Hanabi sees him dating Yukishiro, she might actually give up earlier, than just ignoring her and waiting for her to get tired of it (though yeah, Hanabi is a menhera so she will require a lot of work to get rid of).
And dating on trial basis is actually unfair and demeaning for Yukishiro. Yes, Ichinose hasn't really recovered for years of abuse from Hanabi, but maybe dating someone new like Yukishiro might just really help him see more things in a new light.