How do I forget someone

I (21M) was in a relationship with this amazing girl at school for a little more than a year. Things were great back then and I loved her more than anything. Being lonely at school because I didn’t really fit in having her was the only thing that kept me going. She had been through some difficult times because of her past relationship and which is why I was very gentle with her trying to be the best bf I could.

Then college started and we had to go to different cities and although we promised that we could still date things were messy and the only time we talked was to fight.

So we broke up.

Now in college I have been in a very healthy and loving relationship for the past year, I have great friends and life is good. Still, for some reason I just cannot forget her. It’s like everything reminds me of her and how she would be doing or is she okay? How do i forget about her?

Tl;dr

Can’t forget my ex even though I’m in a great loving relationship