I guess I’ve never understood how a couple could commit their lives together but want to keep finances separate - barring certain special cases where one person has a known problem with money-handling, or finances need to be kept separate for legal reasons, etc.
The only times I’ve had separate accounts from a spouse or live-together partner were when the relationship was in deep trouble and headed for dissolution. Any other time, if your lives are mutual, shared finances are part of the deal. When do separate checking accounts NOT indicate a lack of commitment, or a lack of belief in a future together?