This topic (for talking with your preteen) is one that can be done via various ways and any way that you choose will be good. The key is to just have this talk so that you and your younger one (on their way toward adulthood) have a conversation that is helpful and not awkward. Why? Well, there is a good chance they like someone but they may be wondering how best to determine next steps (aka the dating challenge).
[and yes, this is just to help to get you thinking on this]
“Hey Sweetie, I know this is something you don't want to talk about with me but can I share this with you?” (they may then roll their eyes or in one way or another – they begrudgingly agree) “Thanks . . . I just wanted to let you know that I understand you may want to date someone and that is okay. Although I may make faces or struggle with that in some way, please know that I just don't want anything to ever go wrong for you or for you to someday to have a broken heart. Your Mom and I know that all kids at some point get into relationships. Just know that Mom and I are always here for you and if you can just do us a favor – please be careful. Teen years have so much that unfolds and if you can hold off on getting too serious until after high school, you will find by then you'll have a better sense of who you are and what you want to pursue as you get older.”
So yes – just thinking about what you may want to say and how is not as easy as you may like. That's okay, just think about this and try the approach that makes sense to you. And remember, the approach that keep communications open is always better then ones that shut it down.
Thanks for thinking on this and if I can add one more thing, keep in mind these words from Proverbs 13:20 . . . ”Whoever walks with the wise becomes wise, but the companion of fools will suffer harm. ”