A self-steering north-star metric for a product: Resonant Engagement Moments (REMs).
Interactions, where, if the user were asked in that moment, "Would you proudly recommend this product to someone you care about?" they'd say "yes" without hesitating.
The reason it's about moments is to capture both broad but shallow bits of value that would be easy to forget later, and also deep but rare moments that might not happen that often.
Of course, you don't actually interrupt them at that moment–you construct various proxy metrics to get at it.
But this is northstar to always get closer to.
It's self-steering because these are the touch points that create value.
The more of them you create, the healthier your product.
There are a few reasons someone might be upset if you took the product away, but only one of them is actually love.
First, because they are addicted.
Second, because they already invested a lot of time in this and don't want to do it again.
This is the "sunk cost" value.
It's a kind of reverse value.
It's not that the tool is useful, it's that the user has invested so much time and they'd rather not use anything new even if it's somewhat better.
Every tool that a user has used as a system of record grows this kind of value.
As long as it's good enough, you'll keep using it.
This is not love, it's inertia.
The business might call it "stickiness," but that's just to be polite.
This is actually called "lock-in."
Third, because they find it meaningful and there is no obvious substitute.
This tool does exactly what they need and provides value to them.
If it went away there wouldn't be anything else to fall back on, because it does such a good job of giving them what they need.
These are interactions that nourish the user.
This is love.
Only this third reason counts as a REM.
The "proudly recommend" question filters out the first two.