You expressly stated a need for there to be an (implicit) promise of a relationship.
Being open-minded, thinking someone might just be nice to know, figuring the evening will be pleasant, etc., is all a far cry from that.
And I really think what you describe is really very rare. Who wants to spend an evening, even with good food, with someone you absolutely never want to see again in your life?
"Promise of" is NOT the same as "open to the possibility of" is NOT the same as "already decided against one in advance, but didn't tell the guy while eating on his dime."