Can someone name this clic movie about a girls school?

I seen a movie some years back that intrigued me and Im trying to find out what it is called. It is an older clic movie, Im guessing 50's or 60's. From what I remember it is about a group of girls-especcially one who is very pretty and one who is very plain- and it goes through several years of them growing up. their head mistress or teacher guides them in etiquette and all kinds of cles, including art in which she has obviously had some kind of relationship with the man artist teaching the cl, but it is over. She relates to the pretty blonde girl and is constantly projecting the expectations onto her and grooming her(suggesting that the artist paint the girls picture, as he had done for her) ect, ect. In the end the plain girl ends up being rebellious and SHE ends up with the artist and rubs it in the headmistresses face for underestimating her. ofcourse the lady and the artist still have something going- the girl is pissed that all of his paintings look like the teacher. anyway it was pretty good back then- and i only caught the last half of it. wanted to see it again if anyone knows what the heck im talking about