louise, sorry, but that is really rubbish. It's a totally anachronistic way of looking at history, and you have no possible way of knowing they both 'enjoyed' being queen.
There is, however, plenty of evidence discussed on this thread to show why they might both (and particularly Anne) have ended up in that situation.
Presenting this as a nice little sexist 1950s drama where the woman who 'steals a husband' gets all the blame and the husband himself is blameless is ridiculous.