Shanky, a truly beautiful piece from the heart. It may be simple to love but to fall in love is a truly different matter and is really hard but can be a simply wonderful feeling when it's with the right person.

She is my inner voice
my utmost warmth,
She makes me smile
even when far miles.
^^
This is a lovely opening because this person even though miles away is portrayed as your inner voice so she is like your subconscious mind and also makes you smile which is always a good thing.

Challenged,
by the building up feelings,
love,
my heart she is winning..
^^
You may be challenged but you have decided to take a chance and when we take chances we cannot regret them because at least it's better than the what ifs and should have beens.. It's like your a challenge because she is winning your heart, you are not handing it out. If that makes any sense.
'By the building up feelings' I think 'of' is missing before the word feelings.

And
^^
I feel this was used intentionally to link the last line but that it keeps the reader guessing as to what's coming.

I just hope she knows it.
^^
This is a beautiful ending and I hope she does know it if not too you can always show her.

Great little piece, Em

My vote..

"She is my inner voice
my utmost warmth,
She makes me smile
even when far miles."

i really love this stanza.