Feeling rejected by someone I wanted to be in a relationship with

C: not contacting someone who is special to me
T: I am not good enough for this person
F: resentment, jealousy of their current partner
A: crying, Hurting, Fascinated about them, Beating myself up for not meeting their standards, Comparing myself to the partner chosen by my crush, and overthinking what made them choose this person, Asking myself “what do they have that I don’t have?
R: From time to time I remember interactions I had with this person. Wish it could have been better, Sometimes I forget and move on other times I feel bad about my situation.

How could I help myself with this?