Most Helpful Guy
you're a welcome rarity.
it's a bit of a surprise as it goes against (u. s.) convention; however, i was open to it but more comfortable with "dutch" (each pays their own), tho. it tells someone you're not out for a free meal, which happens far too often.
am sure roots of the custom go WAY back, but expect it had to do with guys (w/money) being the "asker" and girls (w/the goods) being the "agreeer." guys would pay as a means of expressing their appreciation for the girls' time and attentions. this has evolved to a societal norm wrt manners - like holding the door, etc. - in which guys are normally expected to pay.
NOW - there are some who take advantage of this. anyone who's ever had a date order and then have the meal boxed for take-out so they could eat at home (alone), had them bring friends (and expect the bill to be paid by the date), or had a date "eat and dash" (leave w/o notice), will tell you that guys DO watch for such behavior.