Threads merged

I've been on 3 dates with this guy, and things seem to be getting pretty serious (strong connection, talk about the future,etc... ). I left on a trip to Europe for three weeks and now I'm back and he wants to take me out to Brunch, or lunch depending on what time we decide on, so we can catch up on everything.
He has paid for everything all three dates, and I don't want him to burn a hole in his wallet! Although he makes a good amount of money, and that is unlikely, I at least feel the need to offer to pay. He's 29, if that helps for anything. (I'm 21).

Some people say whoever wants to go on the date should be paying. I sort of agree with that. I mean it makes more sense. But I don't want him to feel that I'm taking advantage of him, but letting him pay every time without at least offering.
But then, people claim that it offends some men when women offer to pay.

Also, his birthday happened when I was on my trip so I told him I'd have to take him out on a Birthday dinner. So basically, I'm paying for our next date and I'm sure he knows that. So maybe it's not so bad if he pays for one more?

I don't know. What do you guys think? Should I at least offer to pay?