(1) The girl next door is a distinct stereotype that originated during the World War II era. She is cute like Doris Day; cute and pretty like Debbie Reynolds, but not beautiful and alluring like Elizabeth Taylor. Usually blonde, or light-haired, maybe with a sprinkling of freckles, the girl next door has curves and is very feminine, but not in a sultry, seductive way. Every thing about her is wholesome. She is the girl that waits for the soldier to return home; she is the girl that will make a good mother and homemaker; she is the girl that the young man is not afraid "to bring home" and introduce to his mother.
The America of the 1940s was predominantly composed of first-generation immigrants from Northern Europe with some Eastern Europeans such as Czechs, Polish, Lithuanians, and Southern Europeans such as Greeks and Italians. These Americans retained the Old World values and held to a patriarchal society. Except during World War II when the men were soldiers, women did not work; they were homemakers and mothers, for the most part. Thus, the "girl next door" was well suited for the female role in an American home.
During this time period, there was a song written in 1911 that characterizes the "girl next door" in its second verse:
A good old fashioned girl
with heart so true,
One who loves
Nobody else but you.
I want a girl
Just like the girl
That married dear old Dad.
Two movies in which Doris Day plays the "girl-next-door" type are On Moolight Bay and the sequel By the Light of the Silvery Moon. Doris is the sweetheart of Gordon McRae who makes her wait for him until he establishes himself financially.
Debbie Reynolds is the perky young chorus girl in the American classic, Singing in the Rain with Gene Kelly and Donald O'Connor. She also made Tammy and the Bachelor, whose success brought on more Tammy movies, light romantic comedies with a naive girl from Mississippi.
(2) Women like other women who are non-threatening such as the "girl next door" type because this type of girl poses no threat to their own relationships with males. Another reason is that non-threatening girls can make good friends as they have positive attributes such as honesty and loyalty and unselfishness, and sanguine temperaments.