Don't let the title fool you, as of yet, Shugo Chara stays in the realm of kids' shows, but let me tell you, there's no way that the scene near the end of episode 38 was supposed to mean anything else. I mean, the body language alone makes it clear what's going on. Not to mention the dialogue, with lines like "Want to give it a try?" and "Will it fit?" and all those shots of the key getting closer and closer to the lock interspersed with shots of Amu blushing. And the fact that she breaks it off by saying, "No, I'm scared!" I mean, really. What's the world of anime coming to?