An rather old movie (80's maybe?) and probably (not really sure) French. It's a romantic Comedy with an happy end. A teenage Boy meets a girl at a party and falls in love with her. After that he can not find her anymore and he tells his teacher who helps him with his studies at home so he can graduate about the girl. The teacher gives him some Kind of relationship Tips etc and in the end it is revealed that she is his daughter who is currently abroad or something similar.
In the end of the movie the boy rushes to the local train Station to confess his love, happy ending.
Also some Kind of side Plot with one of the boys Friends who sleeps with the little sister of his girlfriend wich resolves in some Drama etc, also happy end.
Thanks in advance for your help, I can't find the title of this movie anywhere around the web.