Maybe the guys she was with before loved her just as you do,you are not positive they didn't,you are just guessing and comparing them to yourself.And maybe she really loved them in return but doesn't want to upset you by telling you.And it's ok if she did though,she's with you now,that's all that matters.

So what if she sucked **** before she met you.Either accept it,let it go or don't be with her.It's not like she can unsuck them,what do you expect her to do about it now?

How do you even know what she did anyway?

What about it exactly bothers you so much?Maybe you need to end this relationship if it bothers you so much.