Random MCU Headcanon #6
Frigga is a seer, she foresaw that she would die when the Dark Elves attacked. She saw that it would result in Thor and Loki working together. That Loki would take Odin’s place and bring about Ragnarok. And, as contrary as that sounds, that it would be the best outcome for Asgard.
This is why she did little to protect herself against Malekith when she could have used her magic to save herself. She knew it had to be done.
Which is why she faked her death and went on a permanent vacation to get away from the idiot men in her life. But hey, she did it for the