She left

There are several parting options:

1. She left you;

2. You left her;

3. It turned out itself.

Let’s take care of the first reason. Since she left you, it means that either the other guy seemed more attractive to her or you were completely unacceptable for her (you drink, you beat, you are buried behind the young ladies, you earn little — you need to emphasize). In any case, do not twitch!