It is perfectly natural for men to protect women in a dangerous situation. Men routinely put themselves in mortal danger to save a female. This behavior does not work in the military. Every soldier must be equal, able to defend themselves and to protect others.
Also, no soldier wants a 'Helen of Troy' scenario, where a General or even a Sergeant irrationally puts dozens or even hundreds of troops in an impossible battle for no other reason than to rescue his girlfriend or his lover. Love makes men crazy. And irrational decisions in any military situation gets people killed.
I do not believe that women belong in combat. When a man dies, there are a dozen men to replace him. When a woman dies, she takes generations of potential life with her.