Well I can only speak from personal experience on this. I have never accepted my parents’ choices to not attend my wedding. Somehow, I found the strength to forgive them.
They made my wedding about them, when it was about me and my husband. It was selfish of them. But we all do the best we know how to do (I hope), and at the time they thought that was correct. When my child got married, wild horses wouldn’t have kept me away, regardless of what kind of wedding they chose.
There were a few years after I married that my parents and I were “cordial”, at best. At the end of the day, they put their religion before their child, and I don’t understand how that can be justified. That kind of thing damages relationships, not because anyone wants it to be that way, but because that is the way it is. They had their wedding, exactly as they wanted it. It wasn’t for them to have my wedding, too.