In Islam, there is no such thing as a girlfriend-boyfriend relationship. You are either married or you are not. This is what we have to ingrain into our children at the early stage. We should not wait for them to come to us when they are teenagers to ask about girlfriend-boyfriend relationship. At this late stage, even if we forbid them to have such a relationship, how certain are we that they will obey us if they are smitten by someone? Hence, it is important that we teach our children that the only time a girl or boy can have a relationship with a non-Mahram is when they are married! Furthermore, if a girl or boy enters into a girlfriend-boyfriend relationship then he/she is entering into a pre-marital relationship.