According to the Faithfully Songfacts, Journey keyboard player Jonathan Cain wrote this song about the rough relationship being a married man on the road in a Rock band. Sadly, Cain and his wife divorced a few years later, despite him pledging in the song to be "forever yours... faithfully."
Highway run into the midnight sun
Wheels go 'round and 'round, you're on my mind
Restless hearts sleep alone tonight
Sendin' all my love along the wire