Re: Am I overreacting to this prenup?
I agree with most of the prenup. Keeping his and your current assets separate is smart, as is the no-alimony clause. Sorry that some disagree on the alimony, but I've known far too many people completely destroyed and abused by it. If you're no longer wanting to be associated with someone intimately, and no longer wish to share finances, what gives you the right to claim a portion of their future labors? In some unusual circumstances there is justification for alimony, such as a life long stay-at-home-mom who has no marketable skills and is suddenly dumped when she's in her 50's by her cheating wealthy surgeon husband. But these days most adults both have careers and can support themselves independently. No-fault divorce paired with no-fault alimony is an abomination.
It is common in a second marriage or when getting married at an older age to share expenses but to otherwise keep your own finances. So you would each pitch in an agreed upon percentage for housing, food, vacations, etc. It is common to be responsible for your own car. If you go into joint ventures such as buying a rental property or starting a business, you would negotiate percentages up front.
(It is interesting how differently people approach a second marriage when it comes to finances, pre-nups, and alimony compared to a first marriage.)
His attitude, though, seems like a red flag warning about the relationship. I'm glad you're postponing the wedding for a few years.