First part, you is Alex. After , it means the POV has changed. Italics are flashbacks.

Part 4:

When you dream, it's about her. It's always about her. Sometimes the dreams are created by your imagination; sometimes they are memories, always twisted slightly. But not last night. The dream you had last night wasn't a twisted memory, and you know you had it just so that your head could remind you of how much you screwed up, of how you shouldn't have tried to change anything.

The two of you were so happy then, and then everything changed.

"Come on, Alex, let me teach you."
" I don't want to learn," you said, biting your lip. You didn't want to disappoint her.
" Come on, it'll be fun." Then she smiled at you, and any thoughts you had of denying what she wanted were gone. You smiled back, and you said that she could teach you to dance, even though you hated dancing.
" On one condition," you added.
" Anything," she said, and you believed her.
" Let me teach you to play piano."
And she said yes, and that's how the two of you decided to learn to play piano and dance. She was impatient, she wanted you to start learning straight away, but there wasn't time that day.
The next day, after school, she walked home with you, talking all the way. You didn't say much, you've never been one for talking. But her, oh she could have talked forever. And you know, without a doubt, you would have let her. You could have listened to her voice forever and a day.
You arrived at her house, standing slightly awkwardly on the doorstep while she unlocked the front door. She saw you hesitate, turned around and reached for your hand, pulling you lightly into the house. Her hands felt hot against your cold skin, and she looked at you in surprise as she felt how cold you were, and she handed you her sweater without a word. That sweater still sits at the bottom of your wardrobe; you never got a chance to give it back. Actually, the truth is you wanted to keep it, because it reminded you of being near her.
She led you upstairs, taking you to her room. She motioned for you to sit on the bed while she looked through a stack of CDs for something suitable. When she finally found something she liked, she pulled you to your feet, and led you to the spare room. There was more space there. She stood you in the middle of the room while she plugged a CD player in and you stood there, your arms hanging limply by your sides. She giggled lightly at your stance, telling you to relax. You breathed deeply, trying to calm yourself. Dancing and Marissa weren't the best combination for keeping you relaxed. Lately, you'd found yourself tensing up around her, and you weren't sure how long you'd be able to deal with her presence today.
The music began to play: a slow song. She said that you should start out slow; she knew how clumsy you could be. Except for when you were surfing, she said. She told you how you looked breathtaking when you surfed, and you felt warm inside. Then she took your hands, and she moved closer to you, and for a second you forgot to breathe.

She'd been teaching you for a while, and so far you hadn't been doing too badly. Until now, when she went one way, and you went the other, and you ended up in a tangled heap on the floor. You both laughed, even though the impact had kinda hurt your chest. You couldn't move, because her weight was pinning you to the floor. Just like yesterday, you thought, only it wasn't funny then.
She lifted herself off of you, but not completely, and her fingers came into contact with your sides. You giggled, something you didn't do often, and she grinned down at you, and started to tickle you. You've always been extremely ticklish; it's something your friends have used against you on occasion.
You pushed her hands away, laughing even harder. She laughed with you, told you she didn't realise you were so ticklish. You tried to reach for her sides, but she pinned your hands above your head.
" Ah-ah," she said warningly. You relaxed completely, taking her by surprise. She let go of you, and you got to your feet. She looked at you amusedly. Your breathing was still uneven due to the amount of laughing you'd been doing. Her skin was flushed and you thought about how beautiful she looked, but you didn't voice your thoughts. Instead, you cleared your throat, and you said, " Ready for that piano lesson? I think we've done enough dancing for today."
" One more dance?" she asked you, a pleading expression on her face. You almost gave in, but you looked away so you could resist that look.
" I don't like dancing," you replied.
" You like dancing with me, though," she said, leaning towards you a little. Your breathing hitched slightly once more. How was it that she couldn't see the way you felt for her? It was written all over you. You shook your head.
" Not even for you, princess," you said. You'd never called her that before. It had just…slipped out.
" Princess?" she said. " Hmm, I like it."
You smiled, relieved that she hadn't read too much into it. She smiled at you, asked if you wanted a drink before her piano lesson. You nodded your head lightly, your mouth was dry. After a brief visit to the kitchen for a drink, you both walked slowly back to your house.

You've been having trouble sleeping. You can't remember when it started, only that you never had this problem when oyu were still friends with her. Talking on the phone with her before going to sleep had always been comforting, but you didn't realise how comforting it was until you didn't have that comfort anymore. You keep thinking about her. Sometimes the memories are happy, but more ofthen they're sad. They're the things you remember about the end of your frienship, the broken, halting words you threw at her.
Today, though, you were overcome by one memory in particular: The day she first started to teach you to play the piano. Today, you were sitting at the piano, practising for the night's concert, and all you could think about was her hands on yours, guiding them across the keys.

You walked to her house in comfortable silence, neither of you feeling that words were necessary. You liked that. With your other friends, these long silences were always uncomfortable, and they were eventually replaced by equally stilted conversation. With her, though, you felt at peace, and you know that she did too. You followed her to the back room, where a paino stood against the wall, her guitars hanging in a wall bracket above it.
She opened a music book at the first page, a simple melody on the page. You could read music, having taken singing lessons where some knowledge of music theory was necessary, but you weren't entirely sure what to do with it. You told her that, and she just laughed lightly, but not so that you felt you'd said something wrong.
" That's what I'm here for," she said.
As you sat at the piano, with her so close you could feel the heat radiating from her body, you realised that the music on the page in front of you was a scale that was familiar to you. She first of all leaned across you, and demonstrated how to play it. You could feel her breath against your skin, she was so close. And now, when you think abou that moment, you wonder why it took you so damn long to realise how you felt about her.
As you positioned your fingers unsurely on the keys, she gently took your hands and moved them.
" They need to be there, like that," she whispered softly into your ear. As you clumsily played the scale she had showed you, and then turned to look at her, she smiled reassuringly.
"Here," she said, placing her hands on top of yours, and guiding them to the correct positions. After going through this process a few times, she left you to do it on your own, and this time, you didn't make any mistakes. She always had been a good teahcher, you thought, remembering the time she taught you to surf.
You smile at the memory, a full-blown smile unlike the ones you've been wearing recently. She kept teaching you, every afternoon after school, until you felt like you didn't need her help anymore, and even then, she'd sometimes sit and watch while you practised. She asked you to sing once, but you refused. Her judgement meant more to you than anyone else's, and you were scared to open up to her that way. She didn't ask again, she seemed to understand why you didn't want to. She got her wish eventually though, and you find yourself wishing that you had complied with her original request.
It was six months before she told you how she felt about you, and you think about that memory a lot, sometimes inserting your own ending, fresh dialogue. It always ends the same though, with her walking away, slipping out of your grasp.

Her eyes sparkled happily as you laughed at something she said, before the mood changed, and you both became inexplicably serious for a moment.
" I…um…I need to tell you something," she said haltingly.
" You can tell me anything," you'd replied, and at the time you meant it. That was before you heard her next words. She said them so quietly you almost didn't catch them, but the sentiment behind her words would have been clear even if she didn't say it out loud.
" I love you," she said, and for a moment, your world stopped turning. And when it started again, it was spinning too fast, rapidly getting beyond your control.
I...I have to…go," you stammered out, and you practically ran from that room, not pausing to see the look on her face.
She called after you, her voice cracking. You didn't stop, not even for a second. The next day at school, you apologised.

" I'm sorry, Alex, but I just don't feel that way about you,"

Those words, how you hate those words. You can't stand to hear them, even when they're placed in a different context. You couldn't respond that day, even though since then, a thousand different responses have run through your mind. You daydream about them sometimes, imagining that everything happened differently.