She just a cheat. It's in her nature.
That why when you start talking to chick before you date her or try to get her number find out if she ever cheated.
Say something like (After conversation starts up past relationships)" Everybody was young once and made mistake , I was unfaithful once I learned from it and became a better person because of it. I think it shows you matured when you can admit faults in you're past" After that statement she will be like "yeah I messed up in the past once also" or "that's great but I never been in that situation". That's just the first test I run, this will only work on stupid chicks tho because no smart hoe is going to tell the guy she might be feeling that she cheated.
I can't sleep