Help Needed – B String Breaking on Morse Y2D

Hope all of you are safe and doing alright.

I have a Morse Y2D that I absolutely love. I purchased this guitar about a year back on Reverb and am thoroughly impressed with how killer this guitar is. However, I am facing a problem. I have broken the B string at a very interesting place – halfway between the tuning peg and the nut.

Attaching some photos for your reference folks. Can anyone tell me what could possibly be wrong with my guitar?

In the last image, what I have hoped to capture best with my cellphone camera is that there seems to be some discolouration on the string at the exact place where it was seated in the nut. Could this be an issue? I am using a standard 10-46 gauge set and have tuned to standard.

What could I possibly be doing wrong folks?

Appreciate the help and stay safe!

Thanks.