Good listeners are often magnets for people who talk. Significantly, any emotional affirmation given while listening can perpetuate that very talking. Such emotional encouragement can stem from our own cravings and aversions. Therefore this is an opportunity for practice that can benefit us. In particular:
MN62:8.5: This should be truly seen with right understanding like this: ‘This is not mine, I am not this, this is not my self.’
Such practice will at least curtail involvement, but good listeners are often sought out for new problems. Because of this, good listeners often have to do more than merely listen, especially when time is short and other needs more pressing. And in this case the limitless release of the heart can help.
MN127:7.2: It’s when a mendicant meditates spreading a heart full of love to one direction, and to the second, and to the third, and to the fourth. In the same way above, below, across, everywhere, all around, they spread a heart full of love to the whole world—abundant, expansive, limitless, free of enmity and ill will. They meditate spreading a heart full of compassion … They meditate spreading a heart full of rejoicing … They meditate spreading a heart full of equanimity to one direction, and to the second, and to the third, and to the fourth. In the same way above, below, across, everywhere, all around, they spread a heart full of equanimity to the whole world—abundant, expansive, limitless, free of enmity and ill will. This is called the limitless release of the heart.
So after listening, one can ask what love, compassion, rejoicing or equanimity can be found here. And if the answer is "none", well then that complainer will become speechless under your gaze and walk away mute. And if the answer is a thoughtful silence, then that complainer will have found a new perspective to be grateful for.