My parents complain about each other to me, and I don't know what to do.

Sit down and have a family discussion on how they can deal with their emotions instead of putting stress on you

Try talking to them individually and telling the how you feel. Also it might be even better to talk to them together once that is done. So they both know how you feel and where you are coming from.

Maybe you should ask them to be honest with each other to help their relationship grow. You can also inform them that you feel uncomfortable when they complain about the other to u.

Tell them that you feel uncomfortable and would prefer them not to talk about your other parents in a negative way to you

You have every right to inform them that their complaints about each other are bothering you. They have a problem with each other but it's not affecting just them anymore, but you. As your parents, they should see that you are not their therapist or venting machine. Inform them about this, perhaps individually at first.

The best solution is to be honest with them, and say that it makes you uncomfortable. Respectfully.

Sit them both down together and let them know how you feel. I'm sure it will come to a halt when they realize what they're doing is conflicting you.

Hearing your parents complain about each other to you is difficult. Especially because I am sure they both hold a special place for you. Have you tried to talk to them about it? Let each of them know that while you recognize they are having issues with each other, it hurts you to hear it. You can be supportive and there for them but let them know that being supportive doesn’t mean hearing the details of why they are complaining about each other. In the end, you can love them each and have a relationship with each of them without them bringing you into the middle

First, listen carefully to their concerns with empathy, without judging or getting in the middle. Then, reflect and rephrase what they say. Allow them to express their discontent, even to vent. Help the parent explore and express exactly what they're feeling. Support what they're experiencing, that doesn't mean to agree with it, but to respect the reality of their opinion. All this will enable them to gain better perspective and focus on what's bothering them. Encourage them to find constructive ways to discuss and work out the issues they have with each other. That might include getting help here at 7 cups or from a professional counselor.