Lots of good perspective on here. For the record, I have no problem going dutch if there's a second, third, fourth date - or paying in turns.
In this instance, the person upped the ante from lunch to dinner, chose the restaurant ($100 is a chunk of change - this wasn't a diner) and ate twice as much as his date.
I recently had a birthday dinner (my birthday) with a girlfriend who isn't working - she asked how I wanted to celebrate and I suggested a girls' dinner. When the check came, I made it my treat. I am working - and my gift was that I had a great evening with my lovely friend. When she finds a job, she can treat me if she wants to but I was happy to pay.
I don't expect to be paid for by a man - but if I suggest lunch and the other person insists on dinner and then eats a three-course meal (male, female, whoever) then it's polite for them to pay for the meal.