How can I improve a weak fraternal relationship with my brother who doesn't initiate contact, and what should I tell people when they ask why our families don't visit each other, without going into detail?

The Prophet (peace be upon him) urged maintaining kinship ties, even with those who sever them. Therefore, the questioner should persist in maintaining ties with her brother, seeking Allah's pleasure. Doing good, overlooking mistakes, and initiating kind words bring affection and harmony. She should also strive to reconcile her brother and her husband, and tell each of them words that foster affection, even if they are not entirely true, as this is not the blameworthy kind of lying. When asked about the reason for not visiting, she is permitted to use equivocation (tawriya) and insinuation (ta'rid).