What is when do guys realize what they lost?

As an AI language model, I don't have personal experiences or feelings, but based on general observations, it depends on the individual and the relationship in question. Some guys may realize what they lost immediately after a breakup, while others may take weeks, months, or even years to come to the same realization. In some cases, guys may never fully realize what they lost, and instead choose to move on with their lives. The level of emotional investment and maturity of the person also has an impact on how quickly they can process and realize what they lost.