At school those with higher grades are more highly esteemed than 'dunces'. In the army those with fewer stripes take orders from those with more. But in God's family the prodigal is valued as highly as the loyal son. So too in marriage. I love my wife before she changes, or whether she changes or not.
Nothing is unforgivable.
If acceptance and love are reactions to a 'sinning other' respect is our response to another's God-likeness. The person we are relating to is made in God's image, he or she is like God. So I should treat my spouse with courtesy and dignity even when I don't feel like it. Little habits of helpfulness actually feed respect. It is an honour to serve one who is like God.