Why did the speaker move to the country?

Some years ago, I moved to the country. There were not many houses in the neighborhood at that time. The house closest to mine was occupied by a woman. She was about sixty years old and lived all by herself.
   I used to take a morning walk and on my way home the old lady would invite me to her house for a cup of tea. Soon we became good friends.
   We talked about a lot of things when we were together. But my neighbor never mentioned her family. It seemed that she had no relatives and her only life companion was her pet—a dog she called Tommy.
   One night in July I was fast asleep when I was suddenly awakened by the barking of a dog. When I opened the door, I was surprised to find Tommy there.
   When the dog saw me, it started running towards the house of its owner, stopped, barked at me, and started running again. I followed the dog to my neighbor’s house and found that the old lady was lying on the floor.
   Later I learned from the doctor at the hospital that the old lady had had a heart attack that night and that her life would have been in danger if I had not taken her to the hospital immediately.