its been 84 years but here's a kass and queenie post:
i bet early on when they started going on hunts together Kass would imply/state things along the lines of "do not risk your neck for me, because I will not risk my neck for you"
and while queenie was never going to abide by that (I mean look at her) Kass was in denial abt his own behavior. the man has a track record of not being able to leave people hanging, to some extent.
he's DONE it, sure, he's a coward and he's a traitor when he decides consciously to be one, but it's not his instinct. It was a lesson taught to him and it doesn't always stick.
so Kass despite his own statements does end up taking risks for Queenie's sake, even though she by all accounts doesn't need it (autoheal + shields mean she's good at covering her own back) and her own trauma means she never really expects it. she expects to be left to fend for herself.
but he doesn't leave leave her hanging, not even in the beginning, and even though they both know it's the opposite of what he said, she doesn't call him on it. and maybe for a while he rationalizes his behavior to himself (I can think of three good excuses he could use off the top of my head), the truth is:
The second Kass agreed to let Queenie go on hunts with him, he unwittingly and unconsciously committed to worrying abt another person.