If I were to hazard a guess, I'd say it's either:
1. Another guy
2. Big-time personal problems she doesn't want to burden you with
Since you've been together for so long, I would unfortunately lean more toward the former. Reason being, after that long, she would be more apt to be open to sharing just about anything emotional with you, regardless of how hard it is for her.
To just break it off like that in such a cold manner speaks to the possibility of self-rationalization of behavior she's not proud of.
Regardless, you should press her to talk about it. You both need closure, at a minimum.
1. Another guy
2. Big-time personal problems she doesn't want to burden you with
Since you've been together for so long, I would unfortunately lean more toward the former. Reason being, after that long, she would be more apt to be open to sharing just about anything emotional with you, regardless of how hard it is for her.
To just break it off like that in such a cold manner speaks to the possibility of self-rationalization of behavior she's not proud of.
Regardless, you should press her to talk about it. You both need closure, at a minimum.
“Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”
― Albert Einstein
Doing the popular thing is not always right. Doing the right thing is not always popular
― Albert Einstein
Doing the popular thing is not always right. Doing the right thing is not always popular