The Hebrews verse is Scripture. The “leaving our first love” part isn’t.
I offered leaving our first love based on hearing God not seen as he applies his word to our new hearts. We hearing His voice then can walk by faith, the light unto our path , believing the unseen as evidence we have heard God..
Giving that which comes from hearing God not seen, the holy place of God over to men like Nicole the leader of that church required they repent and do the first works. "Believe God not seen" .It was evidence they were not believing God (no faith) but man seen walking by sight after the natural course of this world. .It like the warning of any church is a warning to all the churches in respect to the methodology of the father of lies the spirit of the antichrist.(1 John 2:27-28) We do not need men seen to teach us and in doing in so cause unbelief blaspheming the name of God attributing it to men like Nicole, or the Pope..
Leaving our first love is simply in unbelief (no faith) refusing to take God at his word and believing as a anchor to the soul.
That’s my private interpretation.You obviously have some difference.