Should we care about middle-school lesbianism?

I'm reading this Savage Love article about a mother who found out that her 12-year-old daughter has romantic feelings for a sleepover friend, and the friend reciprocates. Mom wants to know how to handle this---she wouldn't let a middle schooler boyfriend sleep with with her daughter, but what's the appropriate response here? And I'm wondering ... what is she afraid of happening? The girl will not get pregnant, almost certainly will not get any diseases, and if she's got access to the internet or even decent sex ed, she knows how to be safe. Heartbreak could happen regardless of physical involvement. So why does this ping our radar?