they disregard each other / they ignore one another / they fail to attend to each other
1. Third person plural reflexive form of 'desatender' - to neglect, disregard, or fail to pay attention to each other
The two friends desatendem-se whenever they meet in public.
Os dois amigos desatendem-se sempre que se encontram em público.
2. To mutually disregard obligations or duties toward one another
The neighbors desatendem-se and never acknowledge each other.
Os vizinhos desatendem-se e nunca se cumprimentam.