You're not owed sex, and people hate to feel used, whether you believe their perspective is correct or not doesn't change the fact that it's valid to them. You may also be unknowingly failing to support the parts of her that she desires the most. That being said it doesn't seem as though you're purposely trying to hurt her, and I'm not insinuating that you're a bad or entitled person. It simply sounds like you two are incompatible, and if you feel strongly that you're also going unsatisfied in any of your needs that you hold higher priority in then it's better to just call it off before either if you become overly attached and feelings are hurt further than they will be now. There are many people who want similar things to you, if she isn't one of them then you're setting yourselves up for failure.
Side note: the fact she admitted to cheating before is good in the sense that she recognizes her behavior, but it's still a huge red flag that won't simply cease to exist because you're better than her exes. I've learned this the hard way myself. What people do is a reflection of who they truly are, actions speak louder than words, and her actions are suspect unless you'd be unbothered by her failing to be faithful to you now, or in the future