My gf is pretty understanding. I have multiple machines and projects going and she has never argued with me about any of them, she's usually really supporting and gets pretty happy whenever I get something new. I have heard many many times that the person's significant other gets upset over some hobby, project, or spending money on something.
To be fair my wife doesn't give a shit, I think as long as I don't start moving machines into the kitchen or the bedroom or something like that she will likely continue to not give a shit about how many machines I have or how much money I spend on them.
We keep our finances separate, I'd say that 90% of my co-workers are on their 2nd or 3rd marriages and having had the opportunity to listen to them all complain on end about their former and current spouses I came to the conclusion that most marital problems boiled down to either sex or money... with one or both people feeling the other was holding them hostage in that reguard. Even the people who were happy were constantly talking about "getting permission" to buy frigging $50 or $100 items, which to my mind is ludicrous.
So my wife and i have a joint account that we use to pay bills and we both have our own spending accounts and separate savings accounts. I am free to spend as much or as little money on Arcade stuff, and car parts, and other things without asking permission, my wife is free to buy her self spa days, or hiking gear, or plane tickets to visit her sister. It's her money she can do whatever the hell she wants with it.
When it comes to home improvements or vacations or whatever we split the cost. Sometimes if it's something just she wants (like renovating the spare room) she'll pay for it herself, or if it's something just I want (like expanding the finished basement to make room for more machines) I'll pay for it myself.
She was apprehensive about this when we first got married but I was adamant and we're both happier for it. It works well, I highly recommend it.
I very much enjoy being married, for those of you not yet married I have one piece of advice. lots of seemingly "trivial" decisions you make at the beginning of the relationship you'll be stuck with. When you pick the side of the bed you sleep on... that decision is for life.
