Perhaps this has already been answered, but have you made it clear to your lover that you have no intention of leaving your wife? Have you discussed the idea of polyamory with her?
One thing I have noticed seems to happen more often than not is that sometimes the outside person doesn't take the notion of polyamory seriously, and will continue to try to get you to "realize they are your soul mate" or leave your current partner if they just show you eventually that they can make you happier. In a mono-standard world, this is often what people assume is the norm when cheating is going on or when you desire someone other than your partner. The assumption is that your partner isn't "the one" so you are looking for "the one" even if you don't realize it yet.
Your lover may be in a situation where she simply doesn't accept that you still love your wife, and thinks that it is just a matter of time until you realize you really don't love your wife like you do her. This kind of situation can lead to a lot of hurt, and I would advise you to proceed with caution with your lover if she keeps making statements that indicate she wants you all to herself. If you stay with her, even if you are clear and up front with her, you may be leading her on because her paradigm doesn't allow for love for more than one person and she is under the assumption she just has to wait you out.