should I un add her?

hello, me (19M) and this girl (18F) started talking about 3 months ago and after hanging out for a while it started to be me and her getting food then me dropping her off, then me giving her and her friend a ride somewhere then dropping them off and i could tell our relationship was starting to fade. later on there would be days where she wouldn't text me all day and act like she had no interest, then the next day text me (which would usually be to give her a ride) and i don't want to waste my time. I really do like her and want something real with her but I don't want to waste my time on something that's not going to happen. The only thing i can think of is un adding her since i think would be the easiest way to forget her. please let me know what you