Regarding age gap relationships, they can vary widely, and there is no specific "biggest" age gap that is universally experienced. Age differences in relationships can range from a few years to several decades, and what matters most is the mutual consent and understanding between the individuals involved.
Some people are comfortable with larger age gaps, while others prefer smaller differences in age. Age itself doesn't determine the success of a relationship; what's more important is compatibility, communication, and shared values between partners. In many cases, age becomes a minor factor when both individuals are happy and fulfilled in the relationship.
If you have any specific questions about age gap relationships or any other topic, feel free to ask, and I'll do my best to provide information based on my training data.