Is this normal behavior between my girlfriend and her male friend?

So I (30) was sitting down with my girlfriend (32) and a message came through from one of her close male friends. It was in relation to a conversation they had and at the end of the message he had send a few kissy face emojis. Now thing is that my girlfriend is Asian and her male friend is also Asian so i couldn't fully understand the whole context of the message.

They have been friend's since childhood and although i have never met the guy I have never doubted anything until now. We have been together for 4 years and this has really caused me concern and I got very upset and she is also upset.

In fact she got defensive and said that i dont trust her and why would i think she would be doing anything like that behind my back and that it's part of their culture to act like that as friends?

I'm really at a loss here people, to me emojis like that are usually between romantically involved people right?

Is this normal behavior between my girlfriend and her male friend?
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