Well, it's a really tough situation. You could try to find out the root cause of why she is into such inappropriate things. Maybe she has some issues in her life that she is trying to escape through this. But still, cheating is unacceptable. You may also seek some relationship counseling to see if the situation can be improved.
The key here is communication. Sit down with her and ask her why she is doing this. Try to understand her perspective. But also make it clear that this behavior is not acceptable in a relationship. If she is willing to work on it, you can consider giving her a chance. For instance, you could suggest activities like couple's therapy or reading relationship - building books together. But if she shows no intention to change, then it's probably best to end the relationship.
I'm not sure if they are extremely common, but Tinder being a dating app, there is always a possibility of people misbehaving. There are those who are in relationships but still use Tinder to look for something on the side. The 'big dick' part in these stories could be added for shock value or just to make the story stand out more. But overall, cheating stories do pop up from time to time on Tinder, and some might involve this kind of rather vulgar detail.
Most literature promotes positive values, and while there may be some stories that involve cheating, they are usually not glorified. For example, in 'Madame Bovary', Emma Bovary's affairs end in tragedy, showing the negative consequences of such actions.
Cheating is unethical behavior and I don't promote or have positive stories about it. We should focus on positive values like honesty and loyalty in relationships.
I'm not sure specifically what that 'cheating with big dick story' is as it could be something very specific in a particular context or even just a made - up or inappropriate title. It's not something that represents positive or ethical behavior if it involves cheating in a relationship context.
I've heard a story where a girl matched with a guy on Tinder. They started chatting and planned to meet. When they met, she noticed that the guy was constantly looking over his shoulder and acting really nervous. Later she found out through mutual friends that he was in a relationship. It seems like he was trying to have some fun on the side while his partner was unaware. And as for the 'big dick' part, well, it could be just a part of some wild exaggeration in the story to make it more interesting or memorable.
In some of these stories, the cheating involving a 'big dick' mentality could be about power. A person in a position of power at work, say a male boss, might use his status and charm (the 'big dick' factor in a sense) to start an inappropriate relationship with a subordinate. He might think he can control the situation and keep it a secret, but often these things come to light and cause a lot of drama in the workplace and at home if he's married.
One sign is secrecy. If she starts being very secretive about her phone or where she's been, like always taking her phone to the bathroom or not sharing her location. For example, in a story I heard, the cheating girlfriend would never let her partner see who she was texting.