Bringing a Knife to a Resturant on Valentine's Day

I once had a knife in my suit jacket with my ex girlfriend on Valentine's Day. I remember her asking me why I brought it with me to dinner on V-day and I didn't really have a good answer... later on that night a man proposed to his girlfriend and when he went to give her the ring, he couldn't get the ring out of the box because it was tied down. He sat there fumbling with it, with everybody including his anxious girlfriend, for a good minute before I offered him my knife. Needless to say, he was very appreciative and my ex just looked at me with that "Ok ok you were right" look on her face. Now that I look back at it, I don't know why he didn't just use a steak knife, but hey... it worked out alright