In the short story In Another Country, the major said a man must never marry. The main reason he said this was because he was a soldier. His concern was twofold. If he were married in wartime, he would have two worries. One is that he would be distracted in battle, thinking about leaving his wife all alone if he were to die. This would cause distraction, which could easily lead to his death.
The other reason he said a man should never marry is because of a fear of loss. The major is terrified of losing someone he loves, and says so.
This whole thing is ironic in the long run, because he marries a woman much younger than him so that he would not have to worry about losing her. He waits until he is out of the war to get married, for the above reason. He figured he would die first, being the much older person. The irony comes when she dies of illness, leaving him alone. All of those plans to keep from losing the person her loved were pointless.