When I was 24, I decided to go to Peru to do several months of volunteer work. At the end of my time there, I had plans to go hike Machu Picchu with my then-boyfriend, who was going to come visit me from the States. We were going to have separate quarters and I had no intention of engaging in any unchaste acts. By that time in my life, I had lived away from home for 5 years and I was going to daily Mass several times/week and had an active prayer life. You would have thought I was trustworthy, no? Well, my parents decided that it was not acceptable for me to go on an unchaperoned trip with my BF precisely because of the sin of scandal, (not to mention the fact that it might constitute a near occasion of sin, which, when we go to Confession, we resolve to avoid). As a result, my mother and his mother offered to fly down and join us for our trip. Reluctantly, we agreed. I must admit, at the time, I thought it was rather ridiculous and antiquated. However, I think I ultimately agreed because in my heart I knew it was scandalous. Anyone encountering us on that trip would have assumed we were like any other contemporary couple in an unchaste relationship. Furthermore, it could cast doubt in the minds of those who knew us on our commitment to chastity. I am now married to someone else and a mother to his child, and I am so glad that my parents decided to step in - imagine having to tell my husband that I went on an unchaperoned trip with some other man? Although we may have managed to be chaste, imagine how that might change my husband’s perception of me? (And perhaps of our honeymoon? My first unchaperoned trip alone with a man would not have been with him.)
So, from a grateful daughter’s perspective, I say go ahead and insist on a chaperone or refuse to assist with the trip - she will eventually see it as the wise and loving act of a mother/father looking out for her best interest. Remember - our job as parents is to get our kids back to our Heavenly Father and how can we honestly say we are doing that if we are sponsoring or condoning acts of scandal and near occasions of sin?