My wife and I are both 31, we have been together as a 'couple' since we were 13, have lived together since we were 21, and got married at 24, we both know nothing besides each other both as functioning adults and romantically. I've been playing drums since I was 11 and we met during a gig my first ever band was playing at a local underage club a few months into us beginning to play live shows. This always has been and always will be a part of me, she knows that and is fine with that. As long as I keep a job and make time for her I can do whatever I want musically. When we bought our first house she gave me a whole bedroom to keep my drums in and turn into a 'man cave' so I tried to meet her half way and let her do whatever she wants with our bedroom (hell, I just sleep in there lol). Compromise is the key to happiness here, you have to be respectful of each other in everything... Not just drums.
I won't lie, I've 'hid' a small purchase or two over the years (haven't we all?). But I'm not talking a $2k new kit, I'm talking like a set of heads for an experiment or one cymbal. This was always while fully employed and paid well ahead on all bills. As for big purchases she laid out what I find to be very reasonable ground work: you can buy whatever you want as long as it's replacing something or something goes out in it's place. I've always been a minimalist and am far from a gear hoarder, if it doesn't get hit with a stick every time I play I don't keep it, so this is fine with me.
She doesn't come to every gig but she comes to most and is always supportive of me being in live bands rehearsing, gigging, recording, etc.