I've had quite some time to analyze this type of situation in regards to my previous infatuation: cycling, and through forum threads just like this one, came up with some generalizations to consider.
1) Girlfriends support hobbies while wives generally do not.
Notice how all the divorced people praise their new girlfriends? Only a few of them will be singing the same praises if they marry them. When I was dating my wife, she would come to my races and cheer me on, hang out while I worked on my bike or car, and listen to me blabber about cars and bikes to no end. Once we got married, she was too busy to go with me to races or hang out in the garage, and she'd roll her eyes at the mere mention of cars or bikes. This is how women get their man when courting. They take interest in whatever the guy likes. Sure, women are to blame for their unhappiness when they then catch that man and are unhappy with his hobbies, but men still have to face that situation without causing a fight.
2) It's not about money. It's about time.
With a few exceptions, most women aren't gold diggers. As a school teacher, I'm quite positive my wife didn't marry me for wealth. She married me for my personality... and the awesome sex, of course. For most men, she wants to spend time with that personality, and any hobby they're doing which she does not enjoy is competing for that time, at least in her mind. Don't try to keep the balance mathematical, because women don't think that way. You just have to try to figure out what you can do with her and for how long in order to make her feel loved and appreciated. Also, make sure that when you're spending time with her, you keep your conversations about the hobby to a minimum. I had tried to get my wife her own hobby, and reminded her that she only hangs out with her best friend once every few months, but she married me and not her interests or friends.
3) Take a look at yourself.
Is your hobby a pastime or an obsession? After some soul searching, I realized that cycling was an obsession to me. If I wasn't riding, I was working on my bike. If I wasn't working on it, I was shopping for parts to modify it with or chatting on bike forums. While with her, just about every topic reminded me of something cycling related. If we were driving somewhere and I saw someone riding a road bike, I'd glance as if it were a Swedish bikini model.
4) Don't try to drag her into your hobby or drag yourself into hers.
She's not going to enjoy getting her nails done with you if she knows you're not having fun, and you're less likely to enjoy your hobby if you know she's doing it begrudgingly. Doing your favorite hobby while not enjoying it is no better than just not doing your hobby at all. Find something both of you enjoy, and do that to keep each other happy. It may reduce the amount of time and money you spend doing your favorite hobby, but so will driving distances to pick up your kids for partial custody and paying child support checks.
5) A bad balance can ruin your hobby, your relationship, or both.
I know people who got divorced over their hobbies. I know people who quit their hobbies over their marriage. I quit cycling because I stopped enjoying it. Every ride was laced with thoughts of her at home brooding about me not spending time with her. Now that I've quit completely and gained 35 lb, she asks me to go for a ride but I can barely stand looking at the bike anymore. I'm just now considering trying to get a few hours a week in for fitness. I will say that the extra Saturdays with the family have improved our relationship, though. So try to figure out how much time she needs to feel loved, and be happy with whatever time that leaves you to spend with your hobby. One of the greatest things about rocketry is you can spend 30 minutes at a time, days or weeks apart, and still enjoy the results. I couldn't do that with cycling, where a minimum of and hour or two 3 times per week is required to maintain physical shape.
My wife supports my rocketry much more than she did my cycling because I am not overly obsessed with it, and I work the time I spend with is around my family time and wife time.