I think generally a guy should pay since he asked you out in the first place.....plus it gives him a chance to fulfill his 'hunter - gatherer' roll in life. I will usually pay for a couple of rounds of drinks though.
I think once you've formed a relationship and are dating regularly.... splitting the tab or doing dinner at each other's house is very fair.
Going out is VERY expensive. I don't know how guys can afford it very often.
Ofourse not all women drink as much beer as I can....LOL!
