Interesting question.

I have a friend at work who's gay. We all knew she was, but she never talked about it. Then she "fell in love" with some lady and this forced her to "come out of the closet". All my friend's friends are straight and all her "partner's" friends are gay. As a matter of fact, her partner is kinda militant too. Out of kindness to my friend, I went to the mock wedding last year (with others from work). Honestly, the wedding made me sick inside. I couldn't believe I was in that situation.
Whenever talking with my friend's "wife", I'm always friendly and kind, but she always has to talk about gay-this and gay-that. They know I'm a Christian, and how I must feel. I just haven't told them specifically how I feel as a Christian. *sigh* I don't want to make things strange or awkward at work, so I usually just smile and keep my mouth shut. (Btw, they both go to a church nearby that is pro-gay.)

So, my case is very much like the one you've brought up. I pray that God would be gracious to them and show them their sin. And if I'm ever in a situation that requires me to speak out against their lifestyle, I pray that God would give me the wisdom to handle it correctly and in a way that glorifies Him.

__________________
Alex - Orange County, CA - PCA

"I have been crucified with Christ; it is no longer I who live, but
Christ lives in me; and the life which I now live in the flesh I live by
faith in the Son of God, who loved me and gave Himself for me."
Galatians 2:20

Manton - "The sovereign dominion of God is a great prop to our faith."