@AgentKuga
I don't think it's a betrayal.
Remember the end of last chapter, when Kurumi asked Aosoi (the researcher) a favor. It's likely she asked Aosoi to kill her if she ever becomes a burden again.
It wouldn't be the first time Kurumi tried to disappear. Before she lost all strength in her legs, she tried to run away from the group. But since Yuki went to search for her, Kurumi decided that disappearing would only put them in more danger, hence why she wants Aosoi to kill her.
Although, personally, I don't think Aosoi will kill Kurumi. The reason why Bowman-kun answered so quickly is because someone else asked the same question beforehand. My guess is, that someone was Aosoi.
I think Aosoi is currently considering whether to kill Kurumi as requested, or trust Bowman-kun and attempt survival anyway.