Yeah, I'm sure if she'd mentioned to him that she was worried about her period or that she'd read that "safe days" aren't 100% either (especially when still going through puberty), he would've taken it more seriously than going on with no clue anything's wrong until she starts shouting "thank God!"
But really, while I started this series largely because I couldn't stand the comments about what happened right after the previous group dumped it, I find it interesting how this series works hard to not just touch on a broad range of topics, but give a serious look. Such as the personal struggle of wanting to have/keep a certain kind of relationship versus fears of consequences. Or a look at abortion that surprised me. She clearly believes that abortion amounts to killing a child, and has a rather terrifying idea of what that means for the child's soul, but she still feels like she wouldn't have any other choice. I don't often see an opinion like that.