>>6609424Your happiness isn't her job. She left for a reason, maybe because she lost her appreciation for you or found someone she connected with more when your relationship with her was stagnating a little. It's bullshit how it goes and it makes you feel like the world is unfair (it is). Who knows why.
Move on. When you're ready. Be mopey about it for a while. Grow a depression beard. Start working out. Start building personal projects to become a fucking better person.
There aren't plenty of fish in the sea. 90% of everything isn't worth your time including people. A majority of the girls that are worth your time will be unavailable romantically due to forces out of your control. Doing the shit above increases your odds of bumping into someone nice and them taking notice of you. The chance is small but you take that chance every day.