I actually had done this as well (in my past). Honestly, while I don’t know her reasons….there may be something deeper to it. My fiance actually found out – because he knew a friend of a friend of a friend. He knew that I slept with this person 3 yrs before we even met. However, he didn’t know it was him and another guy. So apparently, they were all out together and started talking – and whoops – he found out. We actually broke up for 6 months over it – but honestly, there were reasons for why I did that – one of which, having fun – but reasons that I have not even openly admitted to myself – let alone another person.
I’m a good, loyal, honest, respectful woman and would NEVER do that again. Everyone makes mistakes and have skeletons in her closet. You can’t fault her for this – and I’m sure that you have done some things in your past that she may not like/agree with – but if you really care about her, then you will give her a chance. If you feel like you need to talk to her to move past it – then explain how you feel and ask questions if you need to. But be advised, some of the answers may not be what you want to hear – so tread lightly, because sometimes the unknown (especially the specifics) is better in a case like this.
If she’s not continuing this behavior currently, then I wouldn’t say that you have anything to worry about right now. Like I said, I went through that stage (being “ho-ish), but that was in my early 20s and I was learning about myself and my sexuality. I’m almost 30, and I know what I want and what I need – and that’s the man I am going to marry! Good luck to you!