Personally, PN, I can’t help thinking you are letting your feelings interpret your bible rather than letting the words of the bible determine the bible. And you are using “grace” to hide behind. Paul clearly said, “Shall we continue in sin so that grace may abound? May it never be!” In other words, grace is not an excuse for sin.
IF your friend is living proudly in a homosexual lifestyle and affirming it as absolutely just fine, then Christians have to compare that with what the bible says about homosexuality being a sin.
Do you think that the Bible teaches that homosexuality is a sin?
How do you fall from grace? By sinning? No. "Christ is become of no effect unto you, whosoever of you are justified by the law; you are fallen from grace" (Gal 5:4).