You're moving in with your girlfriend and many people have congratulated you.
You've asked me to do the same but that is something I can't and won't do.
I won't congratulate you because you and your girlfriend will be living in sin.
I won't condone premarital sex, don't ask for my congratulations ever again.
Yes, I have old-fashioned morals that you consider to be out of date.
I won't congratulate you because you're doing something that God hates.