She sleeps around and then (apparently) regrets it. In her own words she's a slut, but is trying to justify her behaviour to make herself feel better. I wouldn't say it's really "your fault", she's just trying to use you as an excuse in a way which would appeal to any man's ego!
F Poste - I think you're overreacting in typical female knee-jerk fashion. My interpretation is he's posting on a message board because some girl's being a tw*t and trying to put the "blame" on him, and he's trying to figure out why. What she does or doesn't do ceases to be "nothing to do with [him]" when she openly discusses it with him, and one would have to be incredibly naive to tell someone they had casually slept with someone 3 times the previous night alone and expect not be considered at least somewhat promiscuous, be they male or female. It sounds to me like she asked TMG's opinion of her based on what she had told him looking for reassurance, but he (as I would have done) took the less-harsh route of turning this around, to which she "branded" herself - probably again looking for reassurance, by hoping that he would disagree. Of course this might not be the case, but to me it seems fairly typical.