Interethnic marriage has has long been happening in such Tapal Kuda regions as Jember, Bondowoso, Situbondo, and Lumajang of East Java province. However, this marriage tends to be in communication failure. If it is not managed properly, it can lead to the conflict that can bring about divorce. Divorce is not only triggered by the economical factors, but also by the failure of communication. For this fact, this research aims at exploring and describing linguistic knowledge, application of interaction skill, cultural knowledge, and factors that can lead to communication failure. To achieve the objectives of the study, it uses a qualitative approach with a focus on ethnographic study of communication. The data were obtained through participant observation and non-participation, as well as interviews with recording technique. The data obtained is transcribed to written data, then analyzed by using the ethnography of communication (speaking grid) and discourse analysis with pragmatic concept. This study yields the findings that the sensitive matters that can trigger conflict constitute lack of linguistic knowledge of local languages owned by each interethnic marriage and lack of interethnic cultural understanding that impact on violations of the principles of politeness and cooperation principles in different cultures thus triggering conflict both within the family and inter-families. Finally, this study concludes that the lack of linguistic knowledge possessed by married couples, especially the understanding of the verbal and nonverbal elements in communicating can lead to communication failure and trigger the occurrence of conflict that impact on the emergence of divorce