So immutable that the RCC has to have these phoney annulment procedures. "What God has joined together ..." Oh, wait a minute, God didn't REALLY join these two together, says man. We found a loophole. Now we can let this philandering ex-husband remarry in the RC church. Just declare ex-cathedra that his first marriage never happened.
Ain't it all convenient when you know what strings to pull?
Some people may abuse the annulment process, but, given that an annulment can take up to two years to secure, and that it is not a simple process, most of those who seek annulments are sincerely seeking to get their lives straight before God.