my mom constantly complains to me about my father...

I'm an adult (38), financially independent and have been living far from my parents for years. I go home maybe 2-3 times a year for a visit. My parents are still married. I'm very close to my father and can be pretty open with him. With my mother, the relationship is a rockier because she's very anxious and judgmental. For example, I no longer tell her when I travel because she needs to know who is taking me to the airport, am I at the airport, am I in the plane, did I land, who's picking me up, etc. So over the years, I've stopped telling her what I'm doing.

When I call home, my mother constantly complains to me about my father. In general, I try to be sympathetic and just let her vent, even if it's annoying or upsetting to listen to, because I'm literally the only person she feels comfortable venting about my father to. To everyone else, she tries to show that she has this perfect marriage. However, sometimes I get really sick of it. We've fought about it many times. During my busier periods, two or three weeks might pass without us talking--yet the moment I call, she just launches right back into how my father is driving her crazy.

I tell her that they should do marriage counseling: she gets angry and says she'd be "embarrassed" to tell a counselor about my father's behavior.
I tell her that I don't want to hear about my father: she says she isn't talking about him, she's just telling me about her day because this is what happened and "well you asked me how I am so I'm telling you."
I tell her that it's inappropriate for her to complain to me about him: she accuses me of talking about her with him (okay we do a little but not that much) and also that it's important to her that I "understand what's happening in the house."
I've also snapped at her a few times to get a divorce or separation: she gets REALLY mad and tells me that I'm selfish and I don't understand what it means to be committed to another person and love someone for decades. Of course, then I yell at her that if she doesn't think I understand, stop bothering me with her marriage problems, which brings her back to the "I need you to understand what's happening here in the house."

Nothing is "happening" in the house. Before the pandemic, a "crisis" might happen because my father had Chinese food for lunch and she'd be super upset that he's going to give himself a heart attack.

Today's fight--I finally hung up on her because I couldn't listen anymore--was about how he wanted to try preserving an avocado in the freezer by mashing it with lemon and putting it in plastic, and that she never mixes lemon and plastic because it's a health hazard. Apparently he totally exploded, said he was done cooking in the house for all time, and went downstairs to sulk. I know why he exploded--my mom is really paranoid about toxic things, like to an extreme level, and it's driving my father crazy.

I'm an adult so maybe I should suck it up and just let my mom vent if that's what she needs. But there are days I can't listen to it. Also, I can't validate her, if that's what she wants, because I just don't agree with her point of view. Advice? Is it wrong for parents to complain about the other parents to their kids, even if the "kid" is already an adult? Is it selfish if I refuse to listen to her venting when I'm the only person she's comfortable venting with?

I think it's one thing to make a complaint and vent about our spouses to someone we trust. It's another to do so chronically. Unfortunately, she is who she is and if she has anxieties about toxicity, you can't really change that about her.

I think it's ok to express that you're interested in knowing how her day has been, as long as she doesn't discuss your dad. It's fine if it's either neutral or positive. Maybe it's been habit forming.

Would she be interested in journaling? LOL I laugh because your mom sounds a lot like mine.. always complaining about her husband (and everyone else). I don't think mine would be interested in it at all. I should ask and see.

Journaling would be GREAT for her. However...she'll never do it. In fact, imagining her doing it...I literally think she'd write five sentences and then need to read them to someone, you know? She's not an introvert at all. Everything she does needs to go through someone else. If no one sees/hears it, etc., it will seem pointless to her...

Omg I feel for you. It’s very unhealthy to involve a child (of any age) in parents‘ disputes and discords. I wonder if you could change topic of a conversation every single time or simply end a conversation like she starts talking about dad, mom I gotta go. If she needs to vent she could do it with her friends or she might benefit from therapy. It sounds so frustrating. Sorry you are in this situation!!!

What she is doing isn’t normal

What you are doing isn’t selfish

Suppose your mother said that she only feels comfortable eating food prepared by you.

Would you be selfish if you refused to prepare all of her meals and send her daily care packages?

Good point... Yeah, she's just a little too unreasonable. In general I try to have the attitude that when I can stand listening to her, I let her complain, and when I can't, I hang up quickly. But then she's left with this expectation that she can complain to me and maybe I've been enabling.

You example reminds me of an exchange I had with her a few weeks ago, when I was carefully attempting to defend my father by putting some of her behavior in perspective. I asked her--"If suddenly dad were to decide that showering in unfiltered water is unhealthy and from now on, you have to buy filtered water jugs and only use that for washing, wouldn't you find it annoying and unreasonable?" Her infuriating response was--"You know, some people do that, just so you know." That's all I got. I was so irritated...

What about just telling her, "Mom, you can't change him so you'll need to find a way to let these things go. If X is important to you, then great. He's his own person with a different set of values and opinions. It's ok to share the same space and not share the same ideas." Then ask her, "So what did you do to make yourself feel better?" Complaining to dad is not a solution. It's controlling. Venting with you is not a solution. It's crossing boundaries.

That is really frustrating but I am not sure what else you can do.

Talking to her doesn't change things. It seems she is lonely and using you for emotional support and/or venting so her troubles don't prey on her mind. And no, she is the parent and should not heap her marital issues onto you. No parent should do so. There is a clear blurring of boundaries that she doesn't seem to be aware of.

Maybe if she had friends she would be less inclined to do this. Seemingly, you are the only one there for her as a source of emotional support.

You may have to tell her you wont ever speak or listen about your father and then back that up with boundaries.

It does seem that you're in a bit of a pickle not wishing to hurt your mom, but as others have pointed out you need to set boundaries with her, otherwise you're hurting your Dad trying not to hurt her.

What about saying something along the lines of
"Mom, I love you BOTH. I don't want to listen to you complain about Dad any more than I would want to listen to Dad complain about you".

Have a short statement written down, and repeat it every time she starts to complain about your Dad.