HomeschoolDad:
Your free will knows this. Your body doesn’t. When you are sleeping, you have no free will — the body and natural instinct take over. It’s not your fault.
And that causes me to ask the question why? According to Catholic Church teaching, it would seem that sexual pleasure is really only supposed to take place between husband and wife. This is one of the reasons masturbation is sinful, because the person provides themself with sexual pleasure. It’s a selfish act with zero chance of procreation.
Of course the sexual pleasure occuring during a wet dream cannot be helped. I do wonder though, why it even occurs? If it’s God’s design that the body needs to get rid of excess sperm from time to time, why does it normally occur in such a way that you have an erotic dream? Isn’t this lustful, even if not through your own choice? Why would God design it in such a way if sexual thoughts are generally lustful unless in the confines of a marriage?