Guys, why do guys use the beating heart emoji when chatting to a female friend?

I asked this guy i know for a favour and he texted back saying he will do it and then he sent another text with a beating heart. I dont think he likes me, he hasn't done anything to suggest he likes me, so why do guys use the heart emoticon? Im not used to it and i dont know what to make of it. Im not bothered by it at all, just thought its strange.
Guys, why do guys use the beating heart emoji when chatting to a female friend?
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