While Sharon was here back in January we started an interesting chat. At Bella's pre-school when they're teaching kids how to apologize, they don't allow the offended party to respond with "That's okay!" because it isn't. It isn't okay. Instead they say thank you for apologizing and remind them not to do it again.
Ever since then Russ and I have been doing the same thing and I think I'm on board. Who started the whole co-dependent "it's okay!" deal? As literal as small children are, for them to hear that they should apologize but then hear that it was actually okay for that to happen is about 5 kinds of mixed messages.