Obviously the man pays. Or should at least be prepared to pay. Fair enough if the lady wants to pay (not that one should let her), but the man should always have in mind that there is an extremely good chance that he is paying! Like Bliss', the missus doesn't pay for anything.
It shows many qualities paying for things, and will always do you good, even if she did ask you out. Since you agreed, you must like her, and if you like her, then you should pay.