My brother's daughter-in-law is like my brother's husband. Netizen said, can I turn my back on my sister-in-law

Sister-in-law and uncle should pay attention to appropriate limits. The relationship between brothers should have been kinship, but because they are married and become two families, there must be a clear line between this sister-in-law and uncle. First of all, two people can't be alone in a room. When two people are together, they will feel uncomfortable and others will be oversensitive. Sister-in-law can't care about uncle and brother. If there is a sister-in-law, she has to avoid suspicion. But according to the secular, sister-in-law and brother-in-law can intervene, which is very strange.