I think the Mother should let it be. They are 13, not 23. Does Mom want it to be serious? My "boyfriends" when I was her age? I talked to one the phone and maybe saw in person once in a while. I am glad that is what it was instead of most of my girlfriends who were already having sex. Stop trying to fix everything for your child and let her learn some life lessons. If it becomes a pattern, then address it.