Heartbroken all over again. Feel like crap.

I met this girl from France last year.
She was on a gap year, but there was a strong chance that she would stay for two.
She's the first girl I've ever been interested in, the only one I've loved.
Went out a few times, texted a lot, liked each other, etc...just as things starting to 'accelerate' it all fell apart.
Her plans for a second year didn't work out, and she went back to France. She's since started university there.

So yeah. Sucks. She's gone, that's the past.
She left in early June, and it hurt as hell at first but it got better, to the point where I've laughed and joked about the whole thing with friends. To the point where overcome interested in another girl again.
I got over her.

Then this week, it all came flooding back.
The hurt, anguish, regret, longing, frustration.
I'm not sure why.

Maybe because it's my first bit of time off I've had since she's been gone. I've been working 50+ hours a week, so maybe that helped to distract me.
Or the film I watched the other day, where the guy meets a cute French girl, but can't be with her.
Or perhaps because I've taken an interest in this other girl, it's bringing back memories?

All I know is I'm fed up of feeling like this, and I want it to end.