It was mostly cuz of the circumstances they were in, novik was off his meds most of the time (since he was selling them also dasha occasionally encouraged him not to take them) which made him a lot less reasonable and more violent which spiraled into him killing her on accident when an argument got physical (⁠ ⁠´⁠◡⁠‿⁠ゝ⁠◡⁠`⁠) he ate her afterwards because he couldnt help it, it wasnt really a choice it was more of an animalistic urge