I think it's a:
A Birthday Candle
Keep me well and I stay whole,
If you take care of the candle then it stays whole.
As I am fit, I keep my role.
A candle that hasn't been used completely can still be reused.
Light’s away and the crowd will sway.
When you blow out the light of the birthday candle then everyone are happy and may jump and clap or even sway when they sing happy birthday.
Feeling your breath I love,
Its a birthday candle... its purpose is for you to blow it out.
Gives me pearls, I see blurred.
While the candle is used the warm wax slides to the side of the candle and can create "pearls" of wax.
Comfort and joy you get from me,
You are happy when you celebrate a birthday
Always taking what I have.
By lighting the candle the fire uses the wax as fuel.
We are taking away the candle wax.
Around my twins, ordinary I am,
Near other candles a candle seems a bit ordinary.
So take us home, make us your own.
Buy some candles for your own birthday.
When I fall, it breaks my heart,
When a candle fall it can break, you even have candles shaped like a heart.
Forever scared I will be.
Not sure about this one...
And when I die, dry faces I see,
If you leave the candle alone then by the time it is finished the party will be over and people will be less excited now.
Never can you fix your blunder.
If you fail to blow out the candle you can't fix that, only try again.
But now, I return to where I'm from,
Wherever you store you birthday candles.
And Then again, Part of me you might see.
If you store what is left of the candle then you might see it again in the next birthday.