User blog comment:Midnight Blaze V/Wizard and Witch Marriages with Muggles/@comment-40129981-20190722091707

Good question.

I don't think that the Ministry of Magic would expect someone in a mixed magic-muggle marriage to live a lie. Generally I think that witches and wizards are advised to use their best judgement and reveal their powers to a loved one if and when they decide to make a life-long commitment. When you trust a Muggle with your secret you're inviting them into the magical world on the understanding that they won't betray you, and muggles that do try and expose the magical community are rarely ever believed anyway... Like when Tom Riddle Snr returned to Little Hangleton claiming that Mereope had bewitched him - all the villagers just brushed him off and assumed that he meant she had lied about her pregnancy. After all, Muggles are keen to deny the existence of things they can't explain and come up with mundane explanations for magical happenings. That's why the wizarding community has remained hidden for so long.

Just like the Ministry doesn't confund/obliviate the parents of Muggleborns I believe they accept reasonable circumstances where a Muggle loved one can be trusted with the existence of magic.