I disagree that the pastor HAS to be married. It's part of pastoral training to give premarital counseling, so they should know what to bring up and topics to discuss. I also don't think there should be another person involved besides the 3, boy/girl/pastor because the more people who are there, the harder it will be to be as open as possible. Also there is the pastor/couple digression he should stick to and none of the information given should leave the walls, much like confession or discussing issues in our lives.
Do you know of any pastors who do 8 weeks of pre-marital counseling? I've never heard of such a thing. The most I've heard of is 3 weeks and there is no way such sessions are going to touch on the same subjects in any kind of depth. Most people don't go to a pastor until they're ready to set the date. After going that far, there are many people who will continue on despite doubts just because they made a decision.
Some of the couples in the pre-marital classes I went to were already engaged, some were married, some were trying to figure out if they were ready to get engaged. These pre-marital classes would be followed by meetings with the pastor if the couple was ready to set a date.
Do you realize that most pastors are not licensed counselors? A pastor should be able to give counsel on scriptural matters and on basics, but an unmarried, non-licensed pastor preparing a couple for marriage? Come on. I can see him saying something like, I'm told wives will feel hurt if you XXXXX. That has almost no meaning unless he's experienced it himself. I have no problem with an unmarried pastor going through the routine questions prior to performing a marriage, but I think it would be ridiculous for a single to try to teach the type of in-depth pre-marital classes I was referring to.
As far as there being other couples there..... it was beneficial. You got to hear other people's experiences, trials, advice. Each week there was homework to do with your partner. That is where some serious in-depth talking would occur. The leading couple was also available for private conversations.
Any good pastor who wants the couple to succeed in their marriage will "rock the boat" simply because they will want to get any issues of importance worked out beforehand rather than later.