Every year my mum makes a big thing about telling me it's their wedding anniversary. Which I obviously don't have on my radar. They usually go out somewhere, which is nice. I get the impression she wants a card from us and a big fanfare, but I just don't think it's something that needs my input. She tends say you seem to have forgotten, but it's our wedding anniversary tomorrow.
My parents were married a long time ( 10 years ) before having me and brother. They argue constantly and moan about each other, and I would say they are both quite miserable.
For context I'm not married, but have been married in the past. They never sent me a wedding anniversary card or even mentioned it. And I wouldn't have expected it at all. (And yes they did like my husband and didn't want us to spilt.)