Briefly, relational dialectics is a conceptual framework within in communications theory that explains difficulties in communications as dialectical tensions.
"Dialect" is derived from Greek philosophers, Socrates and Plato, who posited that truth might be ascertained though rational discourse and reasonable examination of differing thoughts and ideas. This is vastly different from both debate and rhetoric since the former implies emotional commitment to a desired end and intends to result in a victor while the latter assumes full use of rhetorical devices to persuade to a chosen point of view. Dialectic seeks to examine differing ideas to mutually locate truth.
Relational dialectics differs on one humanist point however by asserting that there are multiple truths which can be ascertained and reached. This makes sense if you think of an example in which the ideal may be A but mitigating factors make A impossible while yielding B or C or even D as reasonable alternatives to ideal A.
Two strategies for overcoming the dialectical tensions (conflict of interest; opposing ideas; differing objectives etc) are often readily available. One is to observe interactions within a relationship and interactions without a relationship (i.e., external influences that point a particular opinion etc, like a speech heard by one but not the other in the relationship). Then isolate any aggravating factors or elements that instigate or antagonize dialectal tension. The other is to seek "open-ended, ongoing" dialogue that allows the admittance of variable resolutions.