This isn't original but it works for me. If I am having a feeling, or a worry, or a thought about a person or a relationship that is causing my body to bug me (headache, tense stomache, clenched teeth, etc.), then I need to be sharing that with the person.
Also, one of my favorites from 12 step programs, about whether or not to volunteer something: ask yourself, is it kind, is it necessary, and is it true.