Is it wrong for married people to have friends of the opposite sex?
No. For goodness sakes, no. But one wonders, since it came up, if by "friend" you mean something too close.
I hope that my wife considers all of my male colleagues friends. But there are all kinds of logistical dynamics that she would avoid with men that she wouldn't avoid with women.
For example, we as a staff at Bethlehem don't ride in the car alone with any woman, period. If there are two women, yes. A man and a woman, yes. One woman, No!
My wife would do the same thing. She would feel very awkward being taken to the airport, for example, by a young man if they were alone. If our daughter is with her, not a problem.
Every now and then Noel will ask a woman in the church to come clean house for her. It takes her about four hours. If I'm there, Noel stays there. If Noel has to go, I go. I don't stay in my house with this woman, even though she is a friend and a member of our church. I count her as a friend, but we take steps to be careful.
I don't think married Christians should go out to lunch with friends of the opposite sex. This is really tough in the professional world, but I'll say it anyway. Say, for example, there is a woman lawyer who is married, and she's in a firm with fifty others, some of whom are men. And a guy says, "We need to talk about this case. Let's do lunch." I don't think she should do lunch. I think she should go into his office, leave the door open, and do business there. But if he wants to do lunch, she should say, "Can Jane come along?"
So those are the kinds of things that need to be handled carefully. Yes to the friendship. But we need to preserve the whole array of dynamics that cause our spouses to know that we're jealous for saying that we're married to them. And it's right to be that way.
Say, "I'm just eager to make plain to others, 'I'm not available!' I have a man (or a woman) and I'm very happily married. I don't want to compromise you and I don't want to compromise me."
I think we have become very lackadaisical about that in the professional sphere.