comes from the guy ... so he is the on who is supposed to pay ... some of them got a bad weird habit of inviting the others and then ... I have no money, I forgot my money, or can you pay for me this time?

If it would be just a friendly invitation like let's have dinner, it would be my treat then the one who initiate the invitation had to pay ...

If both of them were just bored and ... what shall we do? Let's have dinner then everyone if both agreed on the idea should pay for him/herself ...

If they are a husband/wife, a bf/gf then the guy should pay ... can't imagine a guy asking his wife or gf to pay for the food or for what is he eating ...

Do not dwell in the past, do not dream of the future, concentrate the mind on the present moment. (Gautama Buddha)