Novel Dating: When do you say "I do"?

I'm dating a novel idea. At first we just flirted. I'd jot down notes, a character sketch, a conversation. But then I'd think of it for no reason. A scene would pop in my head right in the middle of chopping an onion or folding laundry.

It kept calling.

Now it's more than a flirtation. I've written a first chapter and started a second. It is at this point of dating that I get scared, filled with doubts. Are we meant for each other, this novel and I? Can we make it through the hard times? Can I pull it off, and is this novel idea worthy of all the late nights, early mornings, and the hard work it takes to make a relationship strong?

Truth be told, I've never gone all the way with a novel. I've gotten close. I've learned from each unfinished piece, and that's part of why I didn't close the deal with those past darlings. I outgrew them. Or we drifted apart. I typically would then retreat to writing that was less of a time committment - short poems, picture book texts, non-fiction articles - telling myself that the demands of work and kids meant I wasn't ready for a relationship.

I have less time than ever for a novel in my life...and yet my main character won't stop talking to me.

So I ask you, my writing community, how do you know if it's the one? How do you know when to say "I do"?