Any... ANY... any withdrawal of consent between two humans is where I draw the line of "should I" or "shouldn't I".
I'm not sure of what your legal definition of rape is, but for me, if a human being says "no" to sex at any ANY time, a complete and abrupt cessation of sex is mandatory.
But murder is not beneficial to us in 99% of cases.
Murder is a legal definition. Laws change from one place, from one time, from one person... to another.
Termination of human life should only be in self defense or defense of others. If I see someone engaging in physical action against the wishes of another human being, I will use whatever method I have at my disposal to terminate the aggression.
A male lion battles and defeats a rival male lion and, in the process of taking over his rival's family, he kills the rival's cubs. It's common. I would not appreciate it, but I would not stop it.