I had always heard that coco bruni was a good place for dates because they serve nice drinks in a girly atmosphere that most Korean women would like. I think they are right. The place is indeed super comfortable and nice, but not just for girls!
I went there in a group of 6 to celebrate a birthday (surprise) party and bought one of their chocolate cakes (gateau chocolat), and it was amazingly good. A bit on the pricey side (W30,000 for a cake for 6~8 people), but really worth it!
For an extended review go to: https://whereismimiyu.wordpress.com/2015/08/16/cocobruni/