Imogen Heap - The Walk

This seems to be about a woman who is good friends with a man but they find themselves drifting into a romantic relationship even though they for some reason can't 

(married perhaps)

"I don't want to feel like this,
So that makes it all your fault"

"Oh don't make it harder than it already is
I feel a weakness coming on"

Obviously the guy is helping make this a problem for her.

"It's not meant to be like this
Not what I planned at all"

She wants to stay friends and is sure that this will permanently effect their relationship in a negative way. 

Imogen Heap - The Walk 

Inside out, upside-down twisting beside myself,

Stop that now, cos you and I were never meant to me

I think you better leave; it's not safe in here,

I feel a weakness coming on.

Alright then (Alright then) I can keep your number for a rainy day,

That's when its set, no mistakes no misbehaving,

I was doing so well, can we just be friends,

I feel a weakness coming on.

It's not meant to be like this, not what I planned at all,

I don't want to feel like this, Yeah,

No it's not meant to be like this, not what I planned at all,

I don't want to feel like this, so that makes it all your fault.

Inside out, upside-down twisting beside myself,

Stop that now; you're as close as it gets without touching me,

Oh now don't make it harder than it already is,

I feel a weakness coming on.

It's not meant to be like this, not what I planned at all,

I don't want to feel like this, Yeah,

No it's not meant to be like this, not what I planned at all,

I don't want to feel like this, so that makes it all your fault.

Big trouble loosing control,

Primary resistance at a critical load,

On the double gotta get a hold,

Point of no return a second to go,

No response on any level, red alert this vessels under siege,

To a lower lever, systems failed, they've got control,

There's no way out, we are surrounded,

Give in, Give in.....

Freeze, awake here forever, I feel a weakness coming on.

It's not meant to be like this, not what I planned at all,

I don't want to feel like this, Yeah,

No it's not meant to be like this, it's just what I don't need,

Why make me feel like this, it's definitely all your fault.

Feel like this la la la la la la la la

It's all your fault (Feel like this) la la la la la la la la

It's all your fault (Feel like this) la la la la la la la la

It's all your fault (Feel like this) la la la la la la la la

It's all your fault

Two good friends, and one of them ends up falling in love with the other. I don't know that's what I think of everytime I hear this song. I could be wrong, but that's what it means to me.