The concept of what constitutes cheating can vary depending on individual beliefs, cultural norms, and the boundaries set within a specific relationship. In many committed relationships, emotional and physical exclusivity is expected, and actions that betray that exclusivity can be considered as cheating.
While some people may not view self-pleasure or "masturbation" as cheating since it does not involve physical contact with another person, others may see it as a breach of trust and emotional fidelity if it involves thoughts or fantasies about someone else while in a committed relationship.
The key to a healthy relationship is communication and mutual understanding. It's essential to have open and honest conversations with your partner about what is acceptable within the relationship and what actions might make each other uncomfortable. Every couple should define their own boundaries and what they consider to be acceptable behavior within their relationship.
If you are uncertain about how your partner feels about this issue or if you have conflicting feelings yourself, consider discussing it openly and honestly with your partner to gain a better understanding of each other's perspectives and expectations. This communication can help you both establish a shared understanding of what is considered acceptable behavior within the boundaries of your relationship.