I do not know why, but when on a date, it seems like you become a magnet to strangers, that want to introduce themselves, get in on your conversations, then become offended, if any flirts start flying. People will just walk by on the street & suddenly, "Be Greeted's" will just pop up in your interactions. I usually stick to business, then when it's time to do goals, I find an isolated area/table & hope for the best. I always bring a flirty painting along. I don't know if that works anymore, since painting behavior has changed a bit. I know some objects can't be placed as easily. Overall, relationships don't seem to be so worth it, in the game. Sub romantic relationships seem to work a lot more smoothly. I kinda like to follow the flow & see which relationships develop naturally. It's often surprise. The one that flirts my Sim to the pink, will be the one that I will concentrate on & develop.
I don't count the "Enchanting Introduction" relationships. It happened again. My Sim was not Flirty. He was eating & talking to his best friend & suddenly, he enchanted a stranger walking by the table. No time to head the interaction off. It was a instant steamy conversation. Why can't normal flirts be that powerful?