Is sending a heart emoji to guy friends normal for girl while being in a relationship?

I recently found my Girlfriend sending a purple heart emoji to her male best friend as a reply to a complement from him followed by a blowing kiss smiley. I was severely pisssed off on finding this but She told it was out of friendship and purple heart emoji meant nothing. Is it normal for girls in a relation to sent heart emojis to her male friends. I am severely disturbed and her explanations are not going into my head. Please help!!!
Is sending a heart emoji to guy friends normal for girl while being in a relationship?
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