When do you stop picking up the check?

[private joker]

I'm discussing this with my sister and decided to post the debate in order to get opinions.

Obviously on the first date, the guy always pays for the whole thing.

The girl will offer (hopefully), but she will expect -- and it's understood -- that the guy says thanks but I got it. Sometimes she'll say "All right, let me get the next one."

If she does, do you take her up on it? If you pay for the second date, do you expect her to pay for the next one, or do you expect the next one to be Dutch?

What if the girl stops offering and expects you to pay every time?

There always seems to be some point in the relationship when the girl just randomly picks up the check. My last girlfriend (it was about 7 months) only paid like on my birthday and other special occasions, but I didn't mind too much. But if she establishes a pattern of occasionally picking up the check, when should that pattern begin?

There are probably other factors to take into consideration, but this is a hastily written post. Anyway, I think you guys get the gist of it.