My mum and her husband got married 2 years before my husband and I. Before they got married, I didn't have any married couples that I am close to.
After their first anniversary, I saw the gifts and cards that other people gave them and felt guilty that we hadn't given anything as I hadn't realised anniversary gifts were a thing... and the next 3 years we have them nice gifts including this year.
They gave us a gift on our first anniversary last year but this year (1 month after their anniversary) they didn't even give a card. when I mentioned to my mum that I felt a bit hurt by that as other family members sent cards, she said "it's not really a thing, I didn't think you needed to be told that..." it's awfully convenient that she only mentions that it's not a thing when I've already gone to the effort of finding thoughtful things for her... hmmm