Troth is an old English word. It means a promise you keep, the kind you give someone you mean to stand by. It’s where we get “betrothed”, and it shares a root with “true” and “trust”.
We wanted a name that says what he is to you. Not a tool you rent and not a service that can change its terms. A partner who is yours, who learns with you, and who is still himself when everything around him changes.
So: troth.