Jesus entrusted his mother to the disciple whom he loved: John 19:26,27. According to scripture Matt.13:55,56 Jesus had at least six siblings, and the oldest of them being approx. four years younger than himself: did their unbelief lead Jesus to remove his mother from their care?
There are a number of answers based on what tools are used to analyze the text. Having said that, if we compare the witnesses used by the Synoptic writers with the account in the Gospel of John, we find very tight agreement. Each one of the Synoptic gospels agree that later, after several hours of Jesus hanging on the cross, the mother of Jesus was spotted standing far off. The report in John has them much earlier standing near to the cross when the exchange you refer to takes place. Compare Mt.27:55-56; Mk.15:40; Lk.23:49. Notice the context. Each one of these writers report that after Jesus had uttered his final words and the centurion had noticed that he was dead, the women were then found further back in the crowd. "afar off" The agreement of these writers makes a strong case for this logical chronology. Earlier, presumably, while Jesus was still strong enough and coherent, John, the mother of Jesus and others were standing nearer for this exchange which John clearly recalls (Jn 19:25-27). The fact that Jesus recruited John to consider his mother like his own would not mean that the other children were absolved of responsibilities. John may act more like a trustee. In this scenario, there is no need to consider the Synoptics in error because the chronology as reported does allow for a very natural progression that does not necessarily beg for other conjectures. Earlier, John the disciple whom Jesus loved and his mother are standing near. That would make sense in most any normal scenario. Close to the one they loved. Then, hours later, after Jesus' suffering and surrender to death, they had moved further away. It is even possible that soldiers forced them to move further back because they were in the way of their necessary duties to the bodies. That is conjecture on my part. Under any serious interpretation posted, fairy tale would not be a descriptor. There are approaches that seriously consider other formats being employed by the writer to accomplish their task. In this case, there is a very strong case for trusting the witnesses and the material you have before you.
Gail R. O'Day (Women's Bible Commentary, page 527) points out that it is only in John's Gospel that Mary, along with Mary Magdalene and the beloved disciple are at the foot of the cross - in the Synoptics, those of Jesus' acquaintance watch from afar off. Mary Magdalene is a marker, because each of the Synoptics specifically states that she was one of those afar off.
O'Day says that in John 19:26-27, Jesus speaks parallel sentences to his mother and the disciple whom he loves: Woman here is your son; Here is your mother. O'day says both Jesus' mother and the beloved disciple function as symbolic figures and the precise symmetry of Jesus' words reinforces the symbolism of this exchange. In this moment at the foot of Jesus' cross, the past (Jesus' mother) and the future (the disciple) meet. At his death, Jesus ensures continuity between the past and the future.
If John's Gospel is literally true in placing Mary, the beloved disciple and Mary Magdalene at the foot of the cross, then the Synoptics are all in error. If the Synoptics are historically accurate, this dialogue could not have taken place. O'Day resolves this by identifying John's account as symbolic, not literal. The siblings of Jesus have a duty to care for Mary, but that is an issue of literal history, not symbolism.