.22, .25 and .32 are all small enough for the smallest of hands and could fit in a clutch. Get a semi-auto not a revolver.
If you want “small” get a hat pin.
If she’s not going to the range every other week, forget the semi-auto.
Forget the light weight Ti stuff, because she’ll want to get the weapon back on target for the second shot.
.38 S&W w as long a barrel length as you’re willing to carry, up to 4”.
Practice & train with a qualified instructor.....NOT the person you’re sleeping with!
Emotions affect the way instruction is received and delivered.