> at least mention it and give the other person a chance to raise objections

You are not considering the downside of all of this. (Since I get paid for negotiation let me give you my thoughts.) By "giving the other person a chance" you are giving them power over you. Which they could use to extract something from you in exchange for your agreement. Now this may or may not matter depending on the person you are with, but I will point it out so you know that in some cases there could be a downside by "running something by the other party". And yes, there is negotiation in relationships as there is in business.

I'm really happy to say that I don't see my marriage in such adversarial terms. One of the tenets of marriage is that you share and cooperate. I don't spend my time trying to get the upper hand and maintain power, and nor does my wife. That's certainly not something I'm ashamed of. On the contrary. You don't need to be Donald Trump all day.

People and relationships change over time. Keep that in mind. Don't know your age (maybe you have been married for 40 years for all I know) but it's quite possible that your attitude might change later on.

You didn't make that distinction in your "pussy-whipped" comment. Perhaps rather than pussy-whipped, he just hasn't had his marriage degenerate into a state where he feels the need to cling onto every bit of power he can get. I've not been with my wife for 40 years, just ten, but I hope I never reach the stage where I feel the need to avoid discussing things with her in case it means I have to cede some power.

After 20 years together ... I gotta say, our relationship just isn't wired that way. There's negotiation when it's needed, but it's from a position of mutual respect and not adversity. That is, we both recognize each other's needs/wants in the discussion as legitimate and go from there - there's no assumption that one of us is trying to gain power or the upper hand.

It's largely been this way from the start, and has only become more so with time. I couldn't fathom wanting to spend my life with someone I was in a constant power struggle against, or who felt she was in such a struggle against me.

Presumably that power is reciprocal. My wife and I have shared assets/cash flow; there is no way we could have made our budget balance earlier in our marriage without it.

Yes, if you're in a terrible marriage then asking one's spouse about a big purchase could lead to trouble. So what?

Well if such a situation comes up I just won't ask :p The only point of this thread is that it's not unusual to talk about large purchases when it might affect another person, especially when the other person is your spouse.