Should I pay for every third date?

My boyfriend and I have been dating for 2 weeks now. We have gone out on about 4 dates. The first we split the bill but after that he’s paid in full. He’s now proposing to me that I should pay for every third date. I may be taking it too personal but I think counting feels a little ridiculous. I feel like he should want to pay for me and honestly, I’m a bit offended and it feels as though I don’t have enough value on my own.