No, I mentioned how the guy goes for a walk with her on a beach at night, which is a gravely sinful act.
You throw around words like "gravely sinful" so gratuitously. If one is not placed in an occasion of sin by spending time alone with a member of the opposite sex, then it is not sinful. A beach is a public place, and hardly an occasion for most regular people. Perhaps perverts might be tempted to jump into the bushes behind the dunes, but most regular people would not be put in a near occasion on the beach. Do you have some strange belief that given any opportunity, men and women left alone together will jump into eachother's pants? How did you get to know your wife?
Gratuitously: Given or granted without return or recompense; unearned. I have not done that. You may argue the point, but it was not gratuitous. You should learn moral theology before you start arguing with someone otherwise you don't know what you are talking about, and you don't know what you are talking about. I don't mean that in a cold and callous way, just objectively.
It was taught, from the beginning of God creating a covenant with Abraham, that there shall be chaperoning of women and men until married, and if not they shall be in public. Being alone on a beach is neither. Being alone with a woman can be allowed as a proximate occasion of sin if it is necessary (gynecologist, father with daughter, etc.) but if it is not necessary it is always sinful.
As St. Paul teaches us that if any man thinks they can stand, take heed lest they fall. It's a reminder that our chastity is based on God, not on our own efforts. When you tempt God and think you can stand watch out, because after you fall you will see the wisdom in such Divine Revelation.
Oh, and Trinity, I was talking about walking alone with a man on the beach, not walking on the beach. I think even someone like yourself could understand that.