<human>: I found out my friend, who had cheated on his girlfriend with his ex once already, is talking to his ex again on snapchat. His girlfriend (a good friend of mine) initially told me about the first affair and I told her he would do it again but she decided to stay and trust him.

 Im the only one who knows about this current snapchat situation - should I tell his girlfriend? he likely has some sort of intention with talking to his ex. He wouldnt do it just to be friendly or say hello. From what I could see, his ex was the most recent snapchat contact and he had sent something to her.

Can you condense the text into a few key points?
<bot>: Friend cheated on his girlfriend once, is probably doing it again and I'm the only one who knows about the second one