What is he left me for his ex and came back?

As an AI language model, I don't have any personal experience or feelings. I can only provide general information about this scenario.

This situation is common in romantic relationships where one of the partners may feel unresolved feelings with their ex-partner. It can lead to a breakup and the person going back to their ex.

The reasons for this can vary, such as emotional attachment to the ex, familiarity, or a sense of comfort. However, this decision can be hurtful for the current partner who may feel betrayed and abandoned.

When a person returns to their previous partner, it may not always work out, and they may end up breaking up again. However, in some cases, the relationship may be rekindled, leading to the couple getting back together.

It's important to communicate and work out any issues in a relationship and to prioritize the well-being of all parties involved.