I can never remember my spouse's name in my dreams. Why would that be?

I've been with my spouse for years. I'm very happy and very much in love. However, throughout our whole relationship in my dreams my spouse either isn't in my dreams or if they are they don't have a name, have a different name or I actively can't remember it.

I can remember my ex's names in dreams (and annoyingly they show up sometimes). Also when in past relationships this has never happened before.

Any ideas why this might be? It's not particularly distressing just a weird quirk I'm keen to understand. Thanks!