Did you know your significant other when you were both underage? I don't think it should be creepy to acknowledge your partner was pretty underage if you were as well, if you knew them at the time at least. Otherwise that gets into some real dicey territory, like calling someone a pedophile for saying they had a pretty girlfriend when they were both in school together. Do you just have to erase all your memories involving underage people from when you were underage yourself? It just seems ridiculous in that context, like I had had a girlfriend in middle school who was pretty, that's just normal.