What if...

As I was walking downtown to go shopping at the Eatons Centre, I happened to eavesdrop on two girls in their mid-twenties conversation. At first I figured it would be a typical girl conversation - "what are we going to do this weekend!?" or "Oh my God, like I don't know what to wear." As if it were the end of the world or something. Fortunately, it was not at all like that. These girls were talking about a deep dark secret, one that even I feel bad repeating, but it is part of my assignment...
So I decide to follow these girls - I know that is kinda stockerish :S, into Costa Blanca and they are talking about how the one girls boyfriend cheated on her with a close friend. The girl looked horrible once I actually looked up to see her face, she looked devastated and tired. What that poor girl did not know was what close friend it could have been. From what I heard, her friend was trying to convince her that her boyfriend wouldn't do that, that he loved her very much. She was saying "Liz, John would so not do that to you, you know that, he loves you..." The girl constantly kept looking at her phone still with droopy eyes.
I felt bad listening into their conversation, I really did, but I guess I can call this part of my job now? Like my parents always say, school comes first, so world here comes a class full of 30 people ready for eavesdropping in on your conversations.
After I finally left because the conversation died down between the two girls, I thought to myself...What if the close friend the girl's boyfriend cheated on her with was the girl she went shopping with? What if that was the reason why she was convincing her so much? She did seem pretty tense and sympathetic but more towards the boyfriend. What if...