For those suffering from an acute addiction, there may be multiple rehabilitation attempts. Their partner might not appreciate their failure to stop after the first stint, and it can complicate their issues further. For those determined to stop their destructive behavior, continuing to try to stop is one of the best ways for them to proceed. Refusal to believe there is no cure is a good way to look at it, so trying many times could result in success.
Few people really want their spouse to leave them due to an addiction, but it can be too much for the partner to accept when they only see failure to kick the problem. Their own failure to assist the person they love can be a factor that adds to their heartbreak, and it might be that would rather run from that than the behavior of their spouse. Leaving might seem cowardly, but some believe it is the only way to save their own life when their partner continues to let their addiction rule their world.