The likely word is unfailing.
Your voice is faltering.
unexpectedly
Aloof
loveless / unloved, or lonely
Volunteer.
The word is cohabitation.
The adverb could be freely or voluntarily.
"Failing" is a word for not succeeding.
Racetrack, Gatecrash, faltering, barbarian, ballerina, calibrate....
Sportsmanship is a word substitute for spirit of game
There is no one-word substitute in English for "son-in-law."
A word substitute for the sentence "A fault that can be forgiven" is "venial".