The Germans are good at making movies on themes that middle-aged/older women like to hear and think about. I have seen many modern German movies now on the same theme as this: a middle-aged/older woman has been left for a younger woman. Sometimes (as here) the man has also got children with the younger woman. Which makes the older woman feel worthless, as she can no longer have children or be as attractive as the younger woman.
...but then it all resolves itself, as it turns out that the man still loves his old wife, that he misses her, regrets what he has done, does not like his new life with small children in reality, and does not find his young wife that especially attractive anymore. The young woman is often pictured as an egoistic and demanding gold-digger. So he tries to get his old wife back. Sometimes he succeeds, and they come to terms with the fact that he still has to take some responsibility for his new children too, or otherwise (as here) the older woman meets a new man who is much better in all respects. This gives comfort and hope to the very many women past 40-45 who are in this situation.
...but then it all resolves itself, as it turns out that the man still loves his old wife, that he misses her, regrets what he has done, does not like his new life with small children in reality, and does not find his young wife that especially attractive anymore. The young woman is often pictured as an egoistic and demanding gold-digger. So he tries to get his old wife back. Sometimes he succeeds, and they come to terms with the fact that he still has to take some responsibility for his new children too, or otherwise (as here) the older woman meets a new man who is much better in all respects. This gives comfort and hope to the very many women past 40-45 who are in this situation.