Good question! Maybe she wanted Mikau to prove himself by figuring it out/doing something about it. But that's kind of a female doggy(word filter...) move if you ask me. He's the father of your kids, Lulu...you should trust him and love him enough by now. If it were me, I'd write him a note: "Can't sing, something's wrong with my voice. Going to the doctor today about it. Already gave the kids clean water. Speaking of which, I've heard reports of zora eggs being taken by gerudos! Don't let that happen. Take them to work with you if you have to!"
Yes I had too much fun with that hypothetical note xD