If you marry a villager with a diamond wedding ring, it wont count. You can notice this because the achievement till death do us part doesn't trigger. Marriages work properly with a normal gold ring.

Steps to reproduce the behavior:

1. Marry a villager using a diamond wedding ring
2. You get a marriage acceptance reaction
3. You can't use any features that require marriage like working or checking inventory

mca 7.5.5, game version 1.19.2, fabric 0.11.2

latest.log

Because that's an engagement ring, not a wedding ring.