One of my core natures is as a builder and creator. I'm strongly introverted so much of my time is spent in my own head. My best and sometimes worst times are regularly spent by myself. I know you already know many things about introverts, but as a refresher I'd like you to read this.
As a creator, one of the happiest moments we can experience is getting into a state of "flow".
In positive psychology, flow, also known as the zone, is the mental state of operation in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. https://en.wikipedia.org/wiki/Flow_(psychology)
I've heard this flow state described as a process where the mind is so focus on the task at hand, so engulfed in the spirit of the process that all other external processing of our environment and even our own bodily needs can be ignored. The brain puts so much energy and focus into this, that things like the need to eat, sleep, or sometimes even ignoring the restroom (for as long as possible - waiting until my bladder is SCREAMING at me).
I'm quite happy when I'm making progress on my creation(s) as they can often invoke this flow state. While the opposite of the "enjoyment" can certainly happen while working on projects as they can frustrate the heck out of me sometimes and if it ever bleeds into our relationship I'm sorry for that.
I wish I could convey the highs I can experience while in "flow" as strongly as you've likely see my frustrations about the lows. Sadly, without the lows, struggle, up hill battles, cussing at the computer I could possibly never really experience the feelings of success or overcoming that struggle and enjoy them as much as I do.
Between work, family time, children, shopping, housework, sleep and whatever else we fill our days with, it often times feels like I get to apply very little time to this thing that I am truly driven (maybe slightly addicted to) and excited about.
I know you try to give me time to work on these things. There are times you think you've given a Saturday morning or an evening for me to work on my thing. However, sadly for it to truly be a successful session, I need time and space with room to concentrate. An hour before bedtime makes me feel like I shouldn't even try, because it could take at least 30-40 min to get back into the project leaving so little time to be productive that it's not even worth starting. These are times when I decide to blow any amount of time I've been given and just waste it watching a show on Netflix. Not because I don't want to work on my thing, but because I know the amount of effort it will take to get into the flow state will take far too long to make it worth it. If I were to get into flow, I'm then going to want to stay there and likely push past my bed time (which is getting harder and harder to recover from).
I don't want this to sound like this creation/building thing is more important than my family. In fact it's not. If you look at my actions and track record, the amount of time I have pushed aside so I could help you with your endeavors by watching kids, taking on extra shopping trips, house duties as well as the financial obligation (and strain), and still finding time to spend with you in the evenings at the expense of this thing I want to do should prove that my commitment to the family (and you) is still a priority.
I don't know how to close this out an wrap it up, other than to say I love you. I love my children. I also love what I build. I would like to work with you to find a way to balance these items a little better.