If she forgives blitz then her excuse to why her life sucks, no longer works. If she doesn't hate/blame him that means she has to take responsibility for her own mistakes. It's easier to blame blitz for her bad decisions.
Reaching the sad conclusion that perhaps Barbie is simply horrible and doesn't want to be helped.
It's a shame, because I wanted her to do and be better.
LOVED that Loona instantly didn't like her - but she insulted Blitzo, so what do you expect?