The Bible is either true, or it’s not. God has either forgiven us of all our sin and sees us alive in Christ with His righteousness, or He doesn’t. My Bible says that the Lord will never leave us or forsake us, that even when we are faithless, He remains faithful, because He cannot deny Himself, because He indwells us. How does the indwelling Holy Spirit break fellowship? Where does He go? What does He do?
The examples of my position are all around you. Children become estranged from their earthly fathers every day over behavioral issues without ceasing to be their father’s child and without losing his love. But they don’t enjoy the blessings of day to day interaction.
It’s the same for the Church. Who knows how many believers live defeated fruitless lives due to estrangement from their Heavenly Father because of their behavior? They’re still saved and will be taken in the rapture, but here on Earth they’re of no more value to the Kingdom than the dead branches the gardener prunes from the vine (John 15:5-6). Because of the cross, they have eternal union with the Lord but because of their unconfessed sin they don’t enjoy the blessings of day to day fellowship with Him.
The Holy Spirit doesn’t go anywhere, but after a while His advice is no longer sought and His voice is no longer heard. All it takes is confession to restore them, but because they don’t think they should have to they never ask. This is why John wrote that if we claim to be without sin we’re liars but if we confess our sin He is faithful and just and will forgive us our sins and purify us from all unrighteousness (1 John 1:8-9). He was writing to the Church.