I’ve had both of them happen to me in my life.
Honestly I found the callous indifference much more horrible and long lasting. It felt like I was not only (understandably) cut off from the future but any memory she had of our time together was disavowed as well. No matter if the memory was positive or negative.
I understood why she wanted to break up (I acted immature and douchey at the time). However it is the feeling of being treated like I was less than human despite the fact I didn’t do anything fundamentally wrong e. g. cheating, abuse, etc.