It definitely seems like running away (or more generically breaking up from a toxic relationship) is contrary to the wiring of the young adult mind. I was in a toxic relationship in my 20s and had a very hard time leaving, stayed in it for two years past when it was obvious that I shouldn't have.
I suppose that young adults, especially ones that have now defined themselves and their comfort space by the relationship, don't have the confidence it takes to make the right decision. It is frightening - more frightening than the toxic relationship. As you get older and more fully develop that sense of yourself (that we now know lasts well into the mid to late 20s physiologically and perhaps even later emotionally) it's easy and wise to look back and say 'what the hell was I doing'? Or 'she should have run' but the 22-year old is challenged see it that way.