So as a protestant exploring Catholicism the sacrament of marriage and the topic of annulments is a very confusing one.
I would suggest the book Annulment: The Wedding That Was by Michael Smith Foster for an excellent explanation of the Church’s teaching on marriage and decrees of nullity.
On a forum such as this, you are likely to get all sorts of tangents and also probably not a few inaccurate answers. So, I really suggest you check out the book to get a cohesive explanation.
I don’t understand how all protestant marriages aren’t invalid, isn’t the protestant “denomination” founded upon a king who said the state would decide if a marriage could be expunged?
Protestantism is made up of many denominations, with many origins. You refer to one-- the Church of England (now the Anglican Communion).
That’s not exactly what Henry did, either. Henry, a very learned Church scholar in his day, truly believed he was right and the Pope was wrong regarding his marriage, based on his knowledge of theology and church law. Henry got in a spat with the Pope, got himself excommunicated, and then set his own bishops up as the final authority on church matters in England. Of course those bishops agreed with him. Unfortunately Henry died before he healed the rift with the Church.
However I am saying that is the message that is sent out to Protestants ever since the reformation, that divorce isn’t “good” or “wanted” but it is acceptable.
That isn’t a universal message in Protestantism. And, when the couple exchanges vows they say they are marrying for life. The Church presumes the internal disposition of the will matches the words coming out of their mouths. The marriage is presumed valid. It would require external proof to the contrary to bring that consent into doubt.
And also remember the Church doesn’t just say Christian marriages are valid. Natural marriages involving the unbaptized-- Jews, Muslims, Hindus, atheists-- all are valid marriages.
The bar for a valid marriage isn’t as high as you are making it out to be.