Ouch... Chres just struck a nerve calling Karina a 'kid'
Saying things like 'I couldn't die because I had to protect you' also doesn't help (she has a small complex about the whole age and size thing.)
There is also the fact that that Karina simply cannot trust Hark anymore. He pointed his weapon at her first. The 'group' is honestly breaking apart right now. Karina won't trust Hark, it doesn't matter what Chres says, and now that Chres said all this, including basically throwing on her face that he did 'save' them all she is even less inclined to stay with the group.
The situation is already very bad, having to worry not only with the Cultists, but with people who are supposed to be your allies is too much. The dangers far outweighs the benefits for Karina.