Is it normal for a teen to act like this?

Recently my 13-year old niece who is like a sister came to me and told me her troubles..

Basically she is disappointed with life right now. I'm not sure why, she is a straight-A student, healthy, has lots of friends, lives with her normal mother, there is no reason for her to be depressed when everything is going great for her.

But she explained to me that she feels something is missing. She told me she wants someone, a special someone who cares for her, someone who she can talk to and laugh with. Despite all the friends she has, apparently she doesn't feel close enough to talk with them.

I then asked her if she was suffering from the 'All-Other-Girls-My-Age-Have-A-Boyfriend-And-I-Want-One-Too.' syndrome.

She then continued to tell me that she didn't really want a boyfriend in middle school, especially since she knew how much trouble that could lead to, thinking of some naive teenagers she's known. She's incredibly smart, and has actually lectured some of her friends who have gone to second base and lower than home run (possibly). She is disgusted by the fact that kids her age will have sex,because apparently, guys aren't really hot until they've turned 20...

Now, I don't really know if she actually needs this 'someone.' I've suggested for her to talk to her family, but she says it's not the same.

Now, she has suffered from depression for a short time before, when her parents divorced. Now, she is perfectly fine and makes jokes about it now. But I'm somewhat scared that she'll go back into depression because she's 'missing something.' She says she wants 'somebody.' She says she's not really happy with her life.

Is it normal for her to feel like this?

UPDATE: She actually has her father in her life, and has a healthy relationship with both parents.