If you find out your girlfriend is cheating with your best friend, you should first take some time to cool down. Don't make rash decisions. You can then talk to your girlfriend and best friend separately to understand their side of the story. But in most cases, it's hard to forgive such a betrayal.
Here's a story. A white girlfriend, Emma, and a black guy, David, were together. Emma started spending a lot of time on social media chatting with a guy she met online. She started to cancel dates with David, saying she had family stuff. David grew suspicious and when he looked at her social media messages, he saw that she was flirting with this other guy. It was a betrayal of David's trust and ended their relationship on a very sad note.
Here is one possible story. There was a white girl named Lily who was in a relationship with a white guy, Tom. However, she met a black guy named Mark at her workplace. Mark was very charming and they started having long conversations. As time passed, Lily started to develop feelings for Mark and eventually she cheated on Tom with Mark. When Tom found out, he was heartbroken and the relationship ended in a big mess.
There are some movies that touch on themes of infidelity. For example, 'Gone Girl' has elements of a complex relationship where the wife's actions are unexpected and could be seen in the light of some form of betrayal in the relationship, though it's not exactly the same as the 'wife cheats with girlfriend' scenario. But it shows how relationships can be full of secrets and deceptions.
One story I heard was that a girl started getting really close to her boyfriend's best friend while her boyfriend was away for work a lot. She would text him constantly, and eventually they met up behind the boyfriend's back. When the boyfriend found out, he was devastated. It just shows how important trust is in a relationship.
One possible reason could be lack of communication. If they don't communicate well, misunderstandings may arise and lead to one person seeking connection elsewhere. Another reason might be differences in values. For example, if their views on loyalty and relationships are very different, it could cause problems. Also, external temptations, like a new person entering their social circle and showing a lot of interest, could be a factor.
One possible reason could be that she's not fully committed to the relationship in the first place. Maybe she got into it too quickly without really thinking about her feelings for the black guy.
If your girlfriend is involved with 'black stories' in a cheating way, first, you need to have an open and honest conversation with her. Ask her about the situation and her reasons. Maybe there are misunderstandings.
Therapy can also be a great help. A professional counselor can guide the couple through the difficult emotions and help them find ways to rebuild trust. They can also help the couple explore if they can forgive and move forward. In some cases, the couple might decide to redefine the boundaries of their relationship, like opening it up in a consensual way if they both feel it could work.
Communication is key. Regularly talk to your girlfriend about your relationship boundaries and values. Make sure she understands what is acceptable and unacceptable in your relationship.