We don't have majors in the UK, but I changed/restarted my entire university degree, swapping from modern languages and linguistics (specifically, learning Spanish) to Literature.

The "moment" was when I was talking to the administrator about my year abroad which was upcoming the next year. She couldn't find a university that taught linguistics in any spanish-speaking countries, and was trying to convince me that one that taught poetry was linguistics (it absolutely was not). Without continuing that part of my course while abroad, I risked not being able to graduate on my return. And I was very, very bad at Spanish and already extremely nervous thinking I would probably find it too overwhelming. That was the final straw.