Wait, I have to push back on one thing here. You said the hike cost $22 in gas, but that's not really the date's cost, that's just the cost of getting there, which you'd burn either way if you drove somewhere. Same deal with the parking on museum day. If you two would have gone out to eat or seen a movie instead, you're still paying to park or driving there. The real hidden cost people miss is the stuff you buy just because you're out, like a coffee on the walk or snacks at the trailhead. That $31 grocery run for the picnic is the one that actually counts as new spending. The gas and parking feel like date costs but they're really just life costs that show up no matter what you do that night. Not trying to nitpick your whole experiment, because the overall point about small stuff adding up is totally fair. I just see people lumping in gas like it only exists on date night, and that math makes free stuff look worse than it is.

Man, I did the same math when I was staring down a 45 minute each way gig and the gas alone was killing me. Two hours back a day is worth way more than 6k in my book, your mileage may vary but I never looked back.