Don’t you think it all depends how readily your girl friend swoons? You really must take note of her character and decide what turns her on. Also, what has the other guy got that you haven’t? Are you sure it’s his playing that she goes for or his classic profile?
If it’s the sight of you sitting at the piano with bleeding hands that she can tend lovingly with ointments and bandages, try some pieces with double glissandi in them:- Ravel’s Alborado, or glissandi on the black keys:- the third movement of Prokofieff’s 2nd Piano Concerto.
Or she might prefer to see you sweating after a vigorous round with Rachmaninoff’s G minor Prelude, perspiration poring from your manly brow.
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Maybe she would look on you as a hero if you played her the loud, stirring chords on the first page of the 2nd mvt. of the Fantasie in C of Schumann.
However, one of your correspondents had the idea she might just go for sugar and sentiment. If that is so, the middle section of the Fantasie Impromptu should satisfy her, or the Trio of the Funeral March.
A good piece for emotional turbulence, which is romantic and quite easy, is Schumann’s Intermezzo, from Carnival Jest from Vienna - which has been mentioned earlier.
Give her melodrama. Play one of the Chopin Nocturnes and, at the climactic point, bite down on one of those blood capsules they use in films. Then - you are the miserable composer dying of consumption, and she will drag you to her breast and love you for ever (at least, until you die.)
Don’t dare to do any of the Chopin Studies, especially No’s 1 and 4 or the Winter Winds. Don’t attempt La Campanella. You will come a cropper, as I did when I was about ten and fell off my bike in front of a girl I was trying to impress. It’s a searing memory.
Don’t forget, non-pianists just don’t know what is difficult, so don’t waste too much time and energy trying to impress. Appeal to the heart. How about

the ravishing Chopin Barcarolle?