Why can’t I get her out of my head?

Met this girl in the beginning of march and we talked/went out for only 2 weeks before things ended. i really liked her and still think about her daily almost a month later. I’ve been trying to talk to other women but i feel nothing towards them because of her. how do i get over this, and why is she still in my head so long afterwards when we only talked for a short period of time? We haven’t been in contact, can i text her? what do i say? things ended on good terms.
Why can’t I get her out of my head?
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