What guys need to know: That the little things she does is for you, just to make you smile. All she wants to know is that you're thinking of her almost as much as she's thinking of you. Put some effort into this. Cause if she doesn't see, she's still willing to make you happy even if it kills her to do it.
Never try to forget something, no matter how much you want to. There's a reason why your mind won't let it go, even if your heart has. Your memories always serve a purpose, whether you know it or not, and you can't fight that.
What's teenage love? It's staying up late for each other and barely staying awake in class the next day. It's passing each other between classes and stopping to just say hi, and ending up being late to your next lesson. It's going shopping, wandering round hand in hand with a silence that's comfortable. It's watching a movie with his arm slowly creeping onto your shoulders, and you resting your head in his arms. It's walking around at night for no reason at all; his chest, her head, looking at the stars. It's being uncertain as to how long it will last, a risk you're both willing to take, even if it means you'll end up with a broken heart. It's not yet true love, not like, not lust, not infatuation. It's teenage love, here to stay, here to play with our hearts and never to go away.
When you constantly can't stop thinking of him. When you wait for him to go online, or when you wait for a phone call or when you wait for a text. When you see something and it reminds you of him. When you talk about him to your friends, a lot. When you start to read over messages, saved conversations or you replay moments of your life with him in your head. When you realise that when you're out, you look around to see if you "accidentally" bump into him. When you hope to talk late that night again, like you two would used to. When you realise your friends get sick of you talking about him. When you want to hug him again, or kiss him, or just be with him. When you listen to songs and you think "This was our song." When you go somewhere and you reminisce on what happened there with him. When you think of him before you go to sleep. That's when you know you miss him.