he is going out with many girls and it adds up?
well, for calcualtion purpose, his future wife is going out with others at the same time, and others are spending on her….
So it all evens out.
and iyh she will make for him many many meals, 3 /365 a year for litvish, more if you are chassidish, so its a small investment..
if the girl is 18, and she is not comfortable – ask her. It should be her option. “I would like to take you out for Dinner, would that be ok with you, do you prefer milchig or fleishig”