Well, in such fanfictions, often there's a theme of emotional turmoil. The male reader is likely to go through a range of emotions like anger, sadness, and confusion. Also, there might be a theme of self - discovery for the male reader. He may learn more about himself and his boundaries as a result of the cheating situation. And sometimes, there could be a theme of revenge where the male reader tries to get back at the cheater in some way.
One common theme is betrayal. Since it's about a cheater male, the sense of being betrayed by someone you love or trust is a big part of it. Another theme is heartbreak. The male reader usually experiences a great deal of emotional pain.
Betrayal is a very common theme. The shock and pain that the reader character feels when they find out about the cheating is often explored in detail.
One common theme could be betrayal. Since Hugh is a cheater in this scenario, the reader character might experience a sense of betrayal, which can lead to a lot of emotional turmoil and drama in the story.
Often, there's the theme of trust. How the male reader's trust in Blake is broken and how difficult it is to rebuild. Jealousy can also be a theme. If Blake is cheating with someone else, the male reader might experience jealousy. And there could be a theme of growth, where the male reader grows stronger and more independent after the ordeal.
One common theme is adventure. The male reader often goes on adventures with Blake, facing Grimm and other threats. For example, in many stories they might be on a quest to find a lost relic or something similar.
One common theme is redemption. The male reader, who has been abused, often seeks to redeem himself or find a new purpose in the RWBY world. For example, he might strive to become a great Huntsman or Huntress to prove his worth.
A common theme is redemption. Cinder is often seen as a villain in RWBY, so in these fanfictions, the male reader might be the catalyst for her redemption. Another theme is forbidden love, as their relationship might not be accepted in the RWBY world. Power imbalance is also common, considering Cinder's strength and the male reader's usually less - powerful status initially.
In 'rwby x abused male reader fanfiction', a major theme is that of resilience. The male reader, despite the abuse he has endured, shows great resilience in adapting to the RWBY world and its challenges. Another important theme is the exploration of emotions. His past abuse has left him with a complex web of emotions, and the fanfic often delves into how he copes with these emotions in the context of his new relationships with the RWBY characters. There's also the theme of finding a family, as the RWBY characters can become like a surrogate family for the male reader, providing the love and support he may have lacked due to the abuse.
A common theme is power. Since Salem is such a powerful figure in RWBY, many fanfictions explore how the male reader either gains power through their relationship with her or is in awe of her power. For example, in some stories, the male reader might learn dark magic from Salem.
Well, one place to start looking could be fanfiction.net. There are often a variety of RWBY fanfictions there. However, I'm not sure specifically which ones are about a 'cheater' scenario with a male reader. You might have to do some searching through the RWBY section and look at the summaries to find ones that match.