He is old school/chivalrous. Chivalry: courteous behavior, especially that of a man toward women
There are 1,000,000,001 books, articles, and TV shows that tell him to do it.
He really wants to make a good impression.
To show that he has class. Class is not just for Ladies.
His father taught him how to be a man, and how to treat a Lady.
The history of pulling out chairs and opening doors dates back to fashion
There was a time that dresses were inconveniently stiff and wide. The clothes were incredibly restrictive and Ladies needed help with everyday activities. Because of, that men would pull out the chairs to give room between the chair and table. After she is positioned he had to push the chair under her until she is seated. Also, women could not reach door handles because of the wide dresses. So men had to step ahead of women, open the door, and hold it as she approached the door. Additionally, the dresses were too wide to close the door after she entered the room, and the gentleman needed to hold the door to prevent it from snagging the fabric of her dress.
If a man holds the door open, or pulls out your chair, simply smile and say ‘Thank You’. He is being kind and chivalrous, you should be gracious and appreciate the gesture.
