Recently I was asked a couple questions concerning relationships. One question was whether is was OK for a young brother and sister to be together occasionally in a social setting as "just friends". The other question was whether Linda and I were happily married. I tried to answer the questions as well as I could and I thought that others might be interested in the answers. So here are the answers (with personal references removed).
About boy/girl relationships as we call it, we do have some definite feelings based on our experience and observations. I understand that you are not asking about a relationship, simply about doing something as friends. But I think it is better if I try to answer your question in the context of our view for the young people in general.
In Canadian society it is very common for teenagers to form deep emotional relationships, i.e. to fall in love. In our view, this is almost always a mistake because there is rarely a good ending. The most common ending is that after a time they get offended with one another and break up, only to repeat the cycle with someone else. This is preparation for divorce, not for a lasting commitment to one partner. The other outcomes are usually even worse because very few teenagers are ready for the sacrifices and selflessness needed to build a lasting relationship. One Christian young person who got married and divorced while still a teenager told me, "We didn't give ourselves time to grow up."
In the care for the high schoolers we have also observed that they are often reluctant to exercise their spirit strongly around those of the opposite sex. They are too self conscious. When we have separate meetings and camps for the brothers and sisters everyone seems to be much more open and less distracted.
By college age things are different. The young people have experienced more of the Lord and are not as concerned about what others think so we have meetings and activities with everyone together. We feel that it is important that they are together in normal situations and activities. However, we still encourage them to wait to enter into a relationship with someone of the opposite sex.
The Lord has made most of us so that we need a marriage relationship and a family life. But before entering into that we should apply the principle in 1 Corinthians 7 and give our heart to the Lord alone. For most of us, the only stage of life when we can be free to give all our time and hearts to the Lord is when we have just finished our education. We can go wherever the Lord would lead with very few distractions or complications. As soon as we begin to be interested in someone special, things begin to change and once we get married life will never be the same again. At the right time the Lord will lead us into this. A strong church is built with healthy families. But the very same freedom that allows an unattached person to go anywhere according to the Lord's leading means that he or she may not be in one place long enough to build up something solid for the Lord.
My point is, we are only young once. While we are young, why not enjoy being relatively free from the responsibilities and cares of life and give this time to the Lord? When the time comes we will have plenty of time to enjoy the pleasures and rewards of marriage and family life.
You asked my wife and I if we were happily married and I don't think we ever answered your question. The only reason I did not answer immediately was that I wanted to hear how she would respond. I am very, very happy that the Lord brought us together. I appreciate and love her more than I know how to express with words. We had our struggles and I don't know if we would have made it without the Lord and a shared vision of His purpose to give direction to our lives and relationship. But we know that the Lord prepared us for each other and brought us together. I cannot imagine being happier.
So, to answer your first question, I understand that it is possible to be "just friends". The only caution I would give is that I have seen young people who still thought that they were "just friends" after their emotions had gone far beyond that. As soon as even one of the two begins to wonder if the other likes them then they are crossing the line to where emotions begin to get stirred up. It is no longer a matter of "just friends".
I would strongly advise you to carefully observe someone before putting yourself in a situation where the friendship could become special. Watch how he/she treats parents, peers, and younger ones. Does he/she cultivate a relationship with the Lord? Does he/she serve the Lord? Is he/she responsible? Can I live with his/her shortcomings and ideosyncrasies? Be as cool and sober as you can be until you have fellowshipped about someone with your parents and other older saints who genuinely care for you. Once both of you are clear that it really is the Lord's leading that you should enter into a relationship and that this is the right time, then you can let your heart soar.
My wife once told me that she was so happy that the Lord made us so that we could enjoy one another so much. This is exactly how I feel. I hope you and each of the other young people that we try to care for could maintain the same feeling through all the years of your marriage life.